A Fungus Among Us:
Mold Growth in Museum Environments
An independent study carried out to fulfill one of the requirements of the
Additional Concentration in Preventive Conservation offered by the
Winterthur/University of Delaware Program in Art Conservation
Crista A. Pack
Fall 2011
“I’m like a fungus; you can’t get rid of me.”
-Adam Baldwin
PROJECT SUMMARY
Mold spores are everywhere. It may sound dramatic, but there is no escaping them and there is
no way to prevent them from coming into contact with collections. However, there are
methods for managing the environment in order to prevent growth from starting and thriving
on collections items.
A few Native American long weapons in the Alaska State Museum (ASM) closed storage
cabinets were recently discovered to have an unusual fluffy white substance on their surfaces.
This substance had the appearance and characteristics of mold. These objects were comprised
of wood, bone, ivory, leather and feathers; and the white substance was found on each type of
material.
Mold was not initially a suspect on any of these objects, as the collections storage at ASM is
kept close to the desired ranges of 50% RH (± 5%) and 70° F (± 3° F). Therefore, the finding of
mold on ASM objects was perplexing, considering that the guidelines given to museums
indicate that mold should not grow at the humidity conditions maintained by the ASM. The
white substance appeared at some point while the objects were in ASM storage, as they were
noted to be in good condition (without any kind of white substance on them) when they came
into the collection six years ago. Additionally confusing was the fact that the weapons are
stored with other items that do not show any white, fluffy growth.
This raised questions as to why these items were being affected. First and foremost was to
definitively identify the white substances on the ASM objects as mold and not a similar looking
efflorescence or bloom. If confirmed to be mold, then what factors contributed to its growth?
Essentially, the focus of this research was to determine if mold growth is dependent primarily
on RH levels, or if other factors such as mold species, temperature, air flow, and substrate may
contribute to its development.
To answer this, a more thorough investigation of mold was conducted. This study of mold aims
to answer questions regarding the physiology of mold, differences between mold species, and
to determine if all species can be prevented with current guidelines for environmental control.
The research was carried out through a literature review and experimental procedures. Literary
resources were sought out that were directly aimed at collections care, as well as those that
1
thoroughly explained the physiology and characteristics of fungi. Experiments pertaining to the
identification of mold were carried out at the Winterthur and University of Delaware research
labs in Wilmington and Newark, Delaware, respectively.
The anticipation is that the answers to these questions may encourage people to reconsider
their environmental parameters and recognize unique situations that may not fit within normal
guidelines.
2
TABLE OF CONTENTS
Project Summary...................................................................................................................... 1
Table of Contents ..................................................................................................................... 3
Introduction ............................................................................................................................. 5
Goals ............................................................................................................................ 5
Procedure ..................................................................................................................... 6
Outcomes ..................................................................................................................... 6
Experimental ............................................................................................................................ 7
Sampling ...................................................................................................................... 8
Materials and Techniques ........................................................................................... 8
Results ....................................................................................................................... 10
Identifying Collections-Specific Fungal Species
Taxonomy................................................................................................................... 11
Fungal Classifications Relating to Collections ........................................................... 13
The Fungus Among Us ............................................................................................... 14
Fungal Growth and Physiology
Life Cycle.................................................................................................................... 16
Environment ............................................................................................................. 17
Conclusions ............................................................................................................................ 20
Acknowledgements................................................................................................................ 22
References ............................................................................................................................. 23
Appendices
Appendix A: Glossary ............................................................................................................. 25
3
Appendix B: Research Proposal ............................................................................................. 27
Appendix C: Annotated Bibliography..................................................................................... 30
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INTRODUCTION
Conservators at the Alaska State Museum (ASM) in Juneau, Alaska recently began a research
project to study and document “white stuff” that is commonly found on objects in heritage
collections throughout the state of Alaska.1 The common culprits discovered included salt
efflorescences, corrosion, and fatty bloom. However, a few long weapons in the ASM closed
storage cabinets were discovered to have an unusual fluffy white substance which had the
appearance and characteristics of mold. These objects were comprised of wood, bone, ivory,
feather, and stone; and the white substance was found on surfaces of each type of material.
Mold was not initially a suspect on any of these objects, as the collections storage at ASM is
kept close to the desired ranges of 50% RH (± 5%) and 70° F (± 3° F). According to the Canadian
Conservation Institute’s (CCI) “10 Agents of Deterioration” website (2010):
“At 60% RH visible mould growth just possible on some surfaces, but a stable RH
at this value is rare, any intermittent period at less than 55% will stop growth”
and “[for] clean plant based organic materials: mould rate typically requires 80%
-85% RH before mould growth likely at all. E.g., clean textiles, clean paper, clean
wood.”
Therefore, the finding of mold on ASM objects was perplexing, considering that the guidelines
given to museums indicate that mold should not grow at the humidity conditions maintained by
the ASM. The white substance appeared at some point while the objects were in ASM storage,
because they were noted to be in good condition and without any kind of white substance on
them when they came into the collection six years ago. Additionally confusing was the fact that
the weapons are stored with other items that do not show any white, fluffy growth.
Goals
The question this research aims to answer is then, first and foremost, was the white substance
on the ASM artifacts indeed mold? If confirmed to be mold, then what factors caused its
growth? To answer this second question a more thorough investigation of mold was conducted.
This study on mold also aims to answer questions regarding the physiology of mold, differences
between mold species, and to determine if all species can be prevented with current guidelines
for environmental control. The anticipation is that the answers to these questions may help
refine current storage and environmental parameters. The findings of this research may also be
useful to the Alaska State Museum since information gathered about the mold on these ASM
artifacts may aid in future conservation treatments.
1
Results of the ASM project can be found online at http://alaskawhitestuffid.wordpress.com/
5
Procedure
Experimental
In order to better understand the types of mold that can develop on cultural heritage artifacts,
samples were removed from the artifacts at the ASM and sent to Winterthur conservation labs
for analysis. Additionally, samples were taken from several locations at Winterthur for
comparison. The procedures and results will be outlined within the paper. The genus of the
molds grown from the ASM and Winterthur samples were identified by Nancy Gregory, Plant
Diagnostician in the Department of Plant and Soil Science at the University of Delaware. This
pinpointed the specific types of mold found in these instances and helped to determine the
exact environmental conditions in which these species thrive.
Literature Review
The available literature on mold and mold remediation is extensive. Anyone wishing to know
more about a particular aspect of fungal growth and physiology will have no problem finding a
wealth of information on the subject. The information reviewed for this research was culled
specifically from sources that dealt mainly with the problem of mold in cultural heritage
environments. Even with this focus, not all literature could be read in the constrained time of
one semester. Therefore, annotated bibliographies were utilized to gain a sense of the variety
of information out there and to highlight the numerous (and differing) environmental
recommendations. The hope is that this review gives the reader a better understanding of the
variety of parameters that have been developed for controlling mold growth. Additionally, the
taxonomy and growth cycle of fungi common to heritage collections will be summarized.
Outcomes
Researching various fungi that can be found in collections environments will help museum
professionals better understand the potential for mold growth in their storage and exhibition
areas. The anticipation is that the answers to these questions may encourage people to
reconsider their environmental parameters and recognize unique situations that may not fit
within normal guidelines.
Finally, increased exposure to professionals outside the field of art conservation has not only
provided valuable specialized knowledge, but will help increase awareness of the importance of
interdisciplinary work in the preservation of cultural heritage.
6
EXPERIMENTAL
The experimental procedures carried out for this research were performed with the goal of
obtaining specific information regarding the types of mold found in collections and, specifically,
the type of mold occurring on the objects at the ASM. Samples of mold from each of the
affected objects were sent to the research labs at Winterthur for analysis. For comparison,
samples were obtained from two storage locations at Winterthur as well. These were selected
based on recommendations from
current staff.
The first location chosen was Silver
Study Collection I, located on the eighth
floor of the Winterthur estate. This
location had been monitored by a
student during the previous academic
year for relative humidity and
temperature levels.2 During the year, a
black substance was noticed forming on
the air vent beneath the window on the
exterior wall (Figure 1). It was
suspected to be mold and therefore
became a candidate for this study.
Figure 1: Location of sampling area – blackish/brown
accumulation on air vent in Winterthur Silver Study, Collection 1.
The second location was the storage closet located on the third floor of the Winterthur
Research Building, just outside of the objects lab. This was suggested by Winterthur objects
conservator Bruno Pouliot as an ideal location as it is used to house numerous organic artifacts,
is a very small, dark room and has one exterior wall with a covered window. Mr. Pouliot was
unsure of the air flow in the room, but it is a moderately trafficked room as it doubles as a
space for students to observe objects under ultraviolet radiation. This means there are ample
opportunities for the introduction of spores into the room. However, mold growth has not been
observed on any of the artifacts in recent history. Sampling this room would provide an idea for
the types of spores that can be present in a collections storage area, even when conditions are
not met to induce growth.
2
The room was monitored Sara Levin in the Spring of 2011 as part of an assignment for a Preventive Conservation
course during the first year of the Winterthur/University of Delaware Program in Art Conservation curriculum. In
addition to RH and temperature, the other eight “Agents of Deterioration” as outlined by the CCI were monitored.
http://www.cci-icc.gc.ca/crc/articles/mcpm/index-eng.aspx
7
Sampling
In late September, mold samples were received
from the ASM. These came from four affected
items that had been accessioned into the
collection in 2003 (Figure 2). Each sample was
packaged individually and sealed within a small
plastic Ziploc bag to prevent outside
contamination.
Within two weeks of receiving the samples, they
Figure 2: Three of the long weapons on which mold
were transferred to nutritional agar medium for
was found. From top to bottom: 2003-3-9, 2003-3-7,
2003-3-8
regrowth. The theory was that if samples were
transferred to a growth medium, and flourished,
then the substance could be more definitively identified as mold. Additionally, if the transferred
samples proved to be mold, then the growth medium would provide a way to greatly increase
the amount of mold available for study without excessive sampling of the artifact.
Samples from storage spaces at Winterthur were acquired according advice received from a
consulting technician at Ward’s Natural Sciences, a supplier for science education.3 There are
two commonly used methods for collecting mold samples: by rolling a sterile cotton swab over
surfaces to be tested and then rolling those over the agar, or to leave a plate of agar open
overnight in the center of the room to being studied. Both methods were utilized in this study.
For the purposes of this paper, an overall sample was desired that would provide an idea for
what type of airborne fungi would be present in a museum storage environment. Therefore, a
plate of agar was placed in each of the storage rooms being studied. These were left in place
overnight while the museum was closed to visitors (approximately 15 hours). This method
provided the best opportunity to determine what spores are naturally present in the room
without risking contamination from museum guests. Due to the concern of a mold presence on
the vent in the Silver Study room, additional samples were taken from the area where the black
substance was visible.
Materials and Techniques
Mold spores can be found everywhere and the small amounts present on the ASM and
Winterthur samples were not considered a threat. Nevertheless, strict precautions were taken
to ensure people and objects in the lab would not be unnecessarily exposed. All work was
3
Ward’s Natural Sciences consulting technician (Michelle), personal communication, September 27, 2011. Phone:
(585) 321-9143. http://wardsci.com/
8
performed in a fume hood set at the lowest setting.
This was done to prevent spores from escaping into the
environment, as well ensuring the suction was not too
high to lose samples.
Before beginning the experiment, the fume hood was
emptied of all items and cleaned thoroughly with a 1:1
acetone: ethanol solution to remove any
contaminants.4 The samples were removed from their
Figure 3: Example of petri dish with two
samples – 2003-3-6 on the left and 2003-3-7
Ziploc bags and the samples transferred with the aid of
on the right. Nutrient media: sabouraud
clean stainless steel tweezers and/or clean cotton
dextrose agar. Sealed along edges with
Parafilm® M.
swabs. The agar medium chosen for this project was a
sabouraud dextrose agar.5 Two samples were placed in
each petri dish (Figure 3) and closed and sealed with Parafilm®M.6 All of the dishes were then
placed inside a larger Ziploc bag and left in the fume hood for approximately 3 weeks.
After one week small circles of mold growth began to form in the petri dishes. Within two
Figure 4: Agar plates with transferred samples, after eight days.
4
Florian notes that a 70% ethyl alcohol or isopropyl alcohol can be used clean and decontaminate tools (2002, 87).
The 1:1 solution of acetone and ethanol was chosen here because it was already mixed, close at hand and would
also decontaminate the fume hood surfaces.
5
Sabouraud dextrose (SabDex) agar was recommended by the Ward’s Natural Sciences as the nutrient medium
used most frequently in their labs for growing mold cultures.
6
Parafilm®M is a registered trademark for a stretchable plastic film (CAMEO 2008).
9
weeks these circles had spread and formed distinguishable patterns (Figure 4 and Table 2).
Sample Number
2003-3-6
2003-3-7
2003-3-8
2003-3-9
6a
7a
8a
9a
Silver Study
UV Closet
Table 2
Macroscopic Observation of Mold Growth
Observations after 1.5 weeks of growth
Fluffy white circle with dark green center
Dark greenish black, oval shaped, doesn’t have a “fluffy” appearance
2003-3-8 and 2003-3-9 appear to have grown into each other. Large
fluffy white mass with a slight light pink hue. Not symmetrical in shape.
Large dark pink area, flat, not fluffy, somewhat symmetrical circles that
have grown into each other
No visible growth
No visible growth
White fluffy growth at edges – dark bluish green center. Symmetrical,
although grown into side of petri dish.
Concentric circles, nearly symmetrical, fluffy white on outer edge and
middle, dark bluish-green in center
Symmetrical circular fluffy white growth
a – Sample “6” is a second, separate sample, taken from object # 2003-3-6. Sample “7” is from #2003-3-7, “8” from
#2003-3-8, and “9” from 2003-3-9. The exact locations for these samples are unknown, but where taken from
areas of heaviest accumulation to ensure large enough samples were acquired.
Results
After three weeks, most of the molds had filled the petri dishes and samples were running into
each other. Samples were then regrown and analyzed by Nancy Gregory, Plant Diagnostician at
the University of Delaware (UD). She transferred each unique sample to its own plate and
utilized two different types of agar medium: potato dextrose agar and corn meal dextrose
peptone. These had generally proven successful in the UD labs and had produced good results
with most types of indoor molds. A few of the ASM samples did not respond in these nutrient
mediums. A different agar was tried with these – carnation leaf agar. The results of these new
cultures have not yet been determined.
For many of the samples, Ms. Gregory was able to determine the mold down to the genus. The
results of her findings are listed in Tables 3 and 4.
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Table 3
Genus of Mold Cultures from Alaska State Museum
2003-3-6
Chaetomium sp.
2003-3-7
Aspergillus sp.
2003-3-8
Fusarium sp. Transferred to carnation leaf agar
2003-3-9
Fusarium sp. Transferred to carnation leaf agar
6
Bacteria
7
No Growth
8
Aspergillus sp.
9
Aspergillus sp.
Table 4
Genus of Mold Cultures from Winterthur
Organic Object Closet
Not determined: transferred to carnation leaf agar
Silver Study, Room Sample
Sclerotinia
Silver Study, Swab Sample
Memnoniella sp.
The genera identified in these tables will be discussed and examined more carefully in
relationship the overall taxonomy of the Kingdom Fungi.
IDENTIFYING COLLECTIONS SPECIFIC FUNGAL SPECIES
Taxonomy
To begin a discussion of fungi and how the various species differentiate from one another, one
must have an understanding of the terminology. A basic overview is provided here and a
glossary with more complete definitions, additional terms, and images can be found in
Appendix A.
On the most basic level, organisms are divided between five principle kingdoms: animalia,
plantae, protista, monera, and fungi. Most molds belong to the fungi kingdom, which
encompasses multicellular spore-producing organisms with cell walls that contain chitin
(whereas those that contain cellulose belong to the plantae kingdom). Another identifying
characteristic that separates them from species in the Plantae kingdom is that they are
heterotrophic. This means that they cannot produce their own complex carbon molecules
required for nutrition and live by assimilating organic compounds originally synthesized by
other organisms (Florian 200, 9; Dugan 2006, 650). It is for this reason that they are a cause for
concern in heritage collections, since the organic compounds they prefer to assimilate are
11
frequently found there. This includes paper, wood, textiles, basketry and keratinaceous
materials such as feathers and horn.
Beyond kingdom, fungi can be further classified according to six additional categories:
Kingdom
Phylum (aka Division)
Class
Order
Family
Genus
Species
The names given to each phylum, class, and order frequently differ – sometimes dramatically among the literature reviewed. Furthermore, some published classifications have additional
categories of subkingdoms and subphylum that do not exist elsewhere. These shifting
taxonomies are due in part to advances in phylogenetic studies including rDNA, RNA, and
mitochondrial genome sequencing; whereas older classification systems were based mainly on
morphology (Blackwell et al. 2009; Hibbett et al. 2007, 510). It can become quite confusing,
especially for students and non-specialists (Hibbett et al. 2007, 511).
As a result, mycologists from all over the world came together in 2007 and developed an
updated taxonomy system that incorporates a new subkingdom of fungi: the Dikarya (Hibbett
et al. 2007, 510). This subkingdom is then divided into two phyla – the Basidiomycota and
Ascomycota. The Ascomycota are known as the “sac fungi” and are the largest phylum,
containing 75% of all fungi (Taylor et al. 2006). This phylum is further divided into subphylum,
the largest of which is the Pezizomycotina. From there the classifications fan out into a wide
variety of classes, orders, families, and genera. This is where the corroboration between
sources gets tricky.
As a result of these recent and continuously developing categories, many references that have
targeted research on heritage collections are already outdated. This includes standards in the
conservation field such as Mary-Lou Florian’s Fungal Facts (2002). This is not to say that
resources such as Florian’s are not valuable. In fact, from the literary review conducted here,
Fungal Facts proved to be one of the most useful resources available for researching mold on
items of cultural heritage. However, what it does mean is that it can become confusing when
attempting to corroborate the information found with more recent research that utilizes the
newer categorizations. The research conducted here relies heavily on information provided in
literature targeted towards conservation. Therefore, this older terminology will explained and
utilized in further detail below.
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Fungal Classifications Relating to Collections
For nonspecialists, it can be difficult to distinguish mold beyond the subphylum classification.
And even for the trained diagnostician, it can be difficult to identify a fungus beyond its genus.
Therefore, this report will provide an overview of characteristics
of fungal subphylum commonly found in heritage collections.
Fungi that have been looked at by a diagnostician have been
identified down to the genus, and those characteristics will also
be reviewed.
Florian divides the phyla Dikaryomycota into two subphyla:
Ascomycotina and Basidiomycotina (2002, 10). Fungi that
belong to these subphyla can be identified according to their
narrow and septate hyphae – the diffuse, branched filamentous
elements that form the body of the fungus (Figure 5) (Florian
Figure 5: Fungal colony of
branching hyphae (image:
2002, 10). These subphyla live in a wide ecological range,
Florian 2002, 13).
meaning they can survive in a wide variety of environmental
conditions. They are heterotrophic and if they have access to a nitrogen source, they can utilize
their own amino acids to make proteins (Florian 2002, 10). Most fungi in heritage collections
are found in the subphylum Ascomycotina.
Florian identifies the main orders of fungi that have been frequently identified from heritage
collections. These include the orders Sordariales and Eurotiales and each are further described
below:
Sordariales
Genera included in this order are Neurospora, Sordaria, and Chaetomium; all of which have
been found on heritage objects (Florian 2002, 12). The Chaetomium are distinct in that they
have deliquescent asci (Florian 2002, 12). Additionally, they can be characterized by ascospores
that form a mass of coiled branched hairs on top of the ascoma (Florian 2002, 12). They are
damaging to textiles, paper fibers, and any other cellulosic material. They are not typically
encountered on surfaces as anamorphs, but rather as teleomorphs, which have been isolated
on paper that has dirty water damage (Florian 2002, 12). Specifically, Florian states that “the
teleomorphs are encountered when materials have become soiled with dirty water or from
terrestrial burial” (2002, 12).
Eurotiales
Referred to by Florian as “the main culprits,” the order Eurotiales encompasses the genera
Eurotium, Aspergillus and Penicillium (2002, 12). They easily spread through the production of
13
masses of airborne conidia and they are “the most common surface fungi found on artifacts
and archival materials” (Florian 2002, 12).
The Fungus Among Us
Figure 6: Chaetomium sp. – darker
pigmented area in center is likely from the
ascomata
The genera identified from the ASM collections
items (Table 3) fall into these two orders of
Sordariales and Eurotiales. The Chaetomium sp.
discussed in relation to the order Sordariales
was identified in sample 2003-3-6 and is
characterized by darkly pigmented ascomata,
which appear as the dark greenish center in
middle of a dense mass of white, fluffy hyphae
(visible in Figure 6). Colonies are medium-fast
growing in an optimum temperature of 16—25
°C (60.8—77 °F)7 (Crous et al. 2009, 49).
Fusarium sp. (Figure 7) is a genus belonging to the
order Euortiales and was identified in samples 2003-3-8
and 2003-3-9. It is commonly found in soil or on plants,
but has also been reported on items such as
watercolors, old books and parchment, and frescoes in
heritage collections (Florian 2002, 25 and Crous et al.
2009, 99). The survivability of this and other genera is
impressive. Dried Fusarium have been found to survive
up to ten years (in a sealed test tube) and Aspergillus
up to 22 years (Florian 2002, 38; after Sussman 1966).
Aspergillus sp. was found in sample 2003-3-7 (Figure 8),
and samples numbered 8 and 9 (Figure 9). Some
species of Aspergillus are known to produce hard
sclerotia that can withstand inhospitable
environmental conditions. These sclerotia are formed
from masses of pigmented hyphae and store nutrients
for survival. They can be seen within a fungal spot and
may look like black fly specks (Florian 2002, 14). If a
sample of the fungus can be observed under
magnification or with scanning electron microscopy
7
Maximum temperature for growth: 36—37 °C (96.8—98.6 °F).
14
Figure 7: 2003-3-8 and 2003-3-9 – Fusarium
sp.
Figure 8: 2003-3-7, Aspergillus sp.
(SEM), the conidia can be examined. In the Aspergillus genus, the conidia cells form on the tip
of long, thin erect structures called conidiophores. The conidiophore has a rounded head on
which the conidia form; giving the overall structures a hairy look (Figure 10) (Florian 2000, 145).
Aspergillus is a common airborne mold and is frequently
encountered on cultural heritage artifacts, as evidenced in the
results obtained from the ASM. Three of the six molds
identified from the samples provided by the ASM were
Aspergillus.
Figure 9: Sample number 9,
Aspergillus sp.
Common surface fungi such as Aspergillus sp. have been
reported in literature to have conidia with a wide range of
moisture contents – that is, if they are reported at all.
However, there two moisture content groups that dormant
conidia are generally believed to fall into: one is low, with a
6—25% moisture content, and the other is higher, at
approximately 50—80% moisture content (Florian 2002, 33,
52). Those that fall into the latter category are considered
xerophylic (dry-loving) fungi and can germinate even if they
are in an environment with a relative humidity below 60%
(Florian 2002, 33).
“The ability of the conidium to germinate under low substrate moisture content
is attributed to polyols (alcohol sugars) such as glycerol, which are stored in the
conidium of the xerophyllic fungus and act as water regulators by storing water.
The significance of these xerophylic fungi is that they can germinate
unexpectedly on dry materials” (Florian 2002, 33).
The fungi identified from the air samples at Winterthur
(Table 4) were not from the same genera as those identified
on the ASM objects. Sclerotiniaceae, identified from the air
sample in the Silver Study collection is not a commonly
identified fungal growth on heritage collections. Rather, it is
a genera that is typically associated with fruit and vegetable
crop pathogens (Dugan 2006, 63). This is likely a spore that
enters into the building through the air handling system or
on visitors, but doesn’t propagate on the materials within
the building.
Memnoniella sp. is an indoor mold that is similar to the
15
Figure 10: Sample number 9,
Aspergillus sp.
genera Stachbotrys - a common in indoor environments in North America (Barnett & Hunter
1998, 88 and Crous et al. 2009, 190). Memnoniella was not discussed in the literature as a
possible threat to collections material. Stachbotrys was mentioned by Florian as having been
isolated from wallpaper, as well as old books and parchment (2002, 25).
This small study of the Winterthur spaces suggests that the mold spores getting into the
collections areas are not considered a threat to the artifacts. However, this experiment was
very limited in scope and many more samples would need to be taken to make any valuable
assessment of the air spaces. This also doesn’t take into account spores that have already
settled on artifacts from previous environments.
FUNGAL GROWTH AND PHYSIOLOGY
Life Cycle
Figure 11 provides an example of the life cycle of the genus Aspergillus sp. These are often the
main fungi found in heritage collections. Within the diagram in Figure 11, the top circle
represents the asexual reproductive cycle. This cycle is
responsible for the formation of conidia, which are then
distributed through air currents. The bottom circle on
the diagram shows the formation of spores
(ascospores) through sexual reproduction – which can
occur inside of the substrate the fungi is growing on
(Florian 2002, 13).
When the conidia germinate, they form a germination
tube which develops into the hypha. This process is
responsible for the vegetative growth visible on a
substrate. The hyphae grow via tip elongation and form
branching structures that form network-like masses
called mycelium. As the mycelium grows, it produces
hyphae that form groups of asexual conidia which
become airborne. These conidia can sometimes be seen
growing within the fungal mass with the aid of a stereo
microscope (Figure 11). They typically form on the
surface of the mycelium, can grow to 5-50 microns in
diameter, and appear as dusty, colored circles (Florian
2002, 13).
16
Figure 11: Life cycle of Aspergillus sp.
(image: Florian 2002, 13)
The heterotrophic nature of the fungi requires a food source for a fungus to survive and
continue growing. The hyphae are responsible for digestion by secreting enzymes into the
substrate to digest this food source, as well as adsorbing water and oxygen from the substrate
(Florian 2002, 14). It is important to note that these do not come from the surrounding air, but
rather from the substrate itself.
Environment
There are numerous fungal spores in the air around us all the time. In some regions, the fungal
spore count can easily exceed the pollen count. The most notable example of this was in Wales,
where largest fungal spore count ever was recorded at 5.5 million spores per cubic foot (or 194
million per cubic meter) (Blackwell et al. 2009). To put this in perspective, the National Allergy
Bureau identifies a moderate level of outdoor mold spores to be 6500-12999 spores per cubic
meter and a high level to be 13000-49999 spores per cubic meter (American Academy of
Allergy, Asthma and Immunology 2011).
Given that there are so many spores continuously around us, preventing or eradicating them is
not a feasible option to prevent their growth on items of cultural heritage. This being said,
there are ways to limit the amount of spores that come into contact with collections items.
According to Winterthur Mechanical Maintenance Supervisor, Rick Medlock, the air handling
systems for the Winterthur galleries are equipped with a series of filters that remove
approximately 85% of particulates from the intake air.8 This helps in keeping the amount of
spores reaching the collections down to a minimum.
8
There are no statistics available for how many mold spores the filters are capable of removing from the air.
17
Figure 12: Time to the onset of visible mold at various RH percentages. Graph courtesy of Canadian Conservation
Institute: http://www.cci-icc.gc.ca/crc/articles/mcpm/chap10-eng.aspx#toc
Fungal spores that do make their way in can typically survive a variety of environments. The
production of spores is often seen as primarily for distribution, but they are also important to
the survival of the species. Spores allow the fungi to survive in the form of resistant cells that
can withstand environmental conditions not conducive to growth (Blackwell et al. 2009).
However, determining the proper environment may be easier said than done.
CCI states on their website that a minimum of 60% RH is required to start mold growth (Figure
12). Throughout the literature on the subject, most authors publishing environmental
parameters do provide values in a range around 60%. However, while there might be a general
agreement, the specific RH percentages do differ between sources. Table 1 shows a sampling of
conservation resources and the values given.
18
Author
Table 1
%RH Data Obtained from Conservation Literature9, 10
Optimal RH% for
Lowest RH% for
Recommended RH
Growth
Growth to Occur
Parameters
Downey, A. and M.
Schobert (2000)
Above 65%
--
--
Florian, M. (2002)11
--
--
--
Michalski, S. (CCI,
2010)
Nyberg, S. (2002)
Price, L. (1994)
Rekrut, A. (2001)
Strang, T. and J.
Dawson (1991)
Wellheiser, J.
(1992)
--
60%
Below 55%12
Above 70%
70% - 75%
-Above 65%
45%
----
45% - 65%
-Below 65%
--
65% - 85%
--
--
Nyberg amends her parameters slightly by emphasizing that while these are the values
necessary to instigate growth, the relative humidity needed to sustain growth may be lower
(Nyberg 2002, 2-3). However, no specific data is given for what these levels may be.
Florian goes into detail describing the other parameters involved in determining whether
conditions will be right for mold growth. This includes temperature, pH, light, oxygen and
carbon dioxide in addition to relative humidity and water relationships (Florian 2002, 41). In
particular, the effects of temperature and relative humidity together play a crucial role. The
equilibrium moisture content (EMC) is an equilibrium reached in an object between water
vapor in the air and amount of water in the material. It is affected directly by temperature. If
relative humidity remains constant and the air temperature decreases, then water moves into
adsorbent organic materials. Likewise, if the air temperature increases, it moves out of the
9
Each author did not give data for all categories listed in the table. These categories were created to show
differences not only in the parameters given, but in how the information is presented.
10
Data for Price, Rekrut, Strang & Dawson, and Wellheiser was obtained from the Larochette study (Larochette
2003).
11
Florian does not give specific RH% parameters and instead argues that mold growth is dependent on numerous
factors, including temperature, equilibrium moisture content of the artifact, and type of mold. She has
nevertheless been included in the chart as a prominent source for fungal research in heritage collections.
12
Michalski states that any intermittent period at less than 55% will stop mold growth.
19
material, drying it, until diffusion equilibrium is
attained with water vapor in the air (Florian 2002,
43). Therefore, an environment maintaining 55% RH
in a 70 °F room is going to affect the EMC of
materials – and its ability to support mold growth differently than 55% RH in a 60 °F room.
The material itself that the fungus grows on also
plays a major role, as different substrates hold water
differently from one another. The chart in Figure 13
shows that when RH and temperature are kept
constant, some materials will be more likely to
support fungal growth than others.
CONCLUSIONS
This research helped to prove that the white
Figure 13: Effects of RH and EMC on three
different materials – wool, leather and cotton
substance growing on the ASM artifacts was indeed
(image: Florian 2002, 51).
mold. It also provides a better understanding as to
the types of mold that can be commonly found in collections and what conditions are needed
for them to grow.
Most surprising is that mold prevention guidelines focus on RH control, while temperature and
other factors play an equally important role in fungal growth. The wide range of
recommendations for RH parameters in the literature may attest to a misunderstanding of the
relationship between relative humidity, equilibrium moisture content and how fungi obtain
water necessary for activity. Florian points out that “our choice of lower than 70% RH to
control fungal activity is arbitrary. For care of heritage objects, lowering the EMC and RH is the
best we can do for now until we can determine their water activity – another avenue for future
research” (2002, 54).
Also important is the awareness of xerophyllic conidia that have a higher moisture content.
These conidia essentially have stored up their own water supply and not only survive but grow
in drier conditions. Ultimately, it is the combination of environmental factors, material
substrate, and fungal type that determine if mold will grow on a collections item.
The identification of fungal species is difficult and professionals with the experience and
specialized knowledge can provide the most useful data in determining the type of mold
forming on a collections item. Research that is species specific can provide information as to
why fungi are growing on an object and may eventually provide data that pertains to the
20
environmental and material criteria required to sustain growth. However, it does not
necessarily influence treatment options. There are very good resources available that address
treatment and storage issues for mold-infested items, some of which can be found in the
accompanying bibliography. The considerations and options for treatment are numerous and
therefore were not included in the scope of this paper.
The research presented here has additional limitations in that samples of the mold were not
acquired in situ, directly from the objects. The samples were carefully packaged and sealed for
shipping, thereby minimizing the potential for contamination. However, the abundance of
fungal spores everywhere means maintaining a sterile environment between the time samples
were transferred until they were transferred to agar is highly unlikely.
Additional air samples of the storage spaces in Winterthur would provide a more accurate
analysis of the type of spores within the museum environment. Also, monitoring RH and
temperature fluctuations during the incubation period of the samples of agar would provide
more valuable research as to the influence of those conditions on growth. Finally, the
observations recorded here were taken at the macroscopic level. Further studies exploring
microscopic techniques and analysis would be beneficial, especially since a specialist for mold
identification may not always be available.
21
ACKNOWLEDGEMENTS
I am very grateful to a number of individuals who made this research possible this semester,
including my Preventive minor supervisors Bruno Pouliot and Dr. Joelle Wickens at Winterthur
and Ellen Carrlee at the Alaska State Museum. The bulk of the information acquired during this
research could not have been accomplished without the incredible insights of UD plant
diagnostician Nancy Gregory, who graciously shared her knowledge and volunteered to regrow
samples to obtain the most accurate information possible. Additional thanks to the following
individuals for sharing their expertise and opinions with me: Rick Medlock, Winterthur
Mechanical Maintenance Supervisor; the consulting technicians at Ward’s Natural Sciences; Dr.
Kirk Czymmek, Associate Professor at University of Delaware Department of Biological Sciences;
Dr. Tom Evans, UD Department of Plant and Soils Sciences faculty.
22
REFERENCES
American Academy of Allergy, Asthma and Immunology. NAB Scale. Online:
http://www.aaaai.org/global/nab-pollen-counts/reading-the-charts.aspx (Accessed
12/13/2011).
Blackwell, M., R. Vilgalys, T. Y. James, and J. W. Taylor. 2009. Fungi. Eumycota: mushrooms, sac
fungi, yeast, molds, rusts, smuts, etc.. Version 10 April 2009.
http://tolweb.org/Fungi/2377/2009.04.10 in The Tree of Life Web Project, http://tolweb.org/
(Accessed 11/26/2011).
Crous, P. W., G. J. M. Verkley, J. Z. Groenewald, and R. A. Samson, eds. Fungal Biodiversity.
Utrecht, The Netherlands: Fungal Biodiversity Centre.
Dugan, F. M. 2006. The Identification of Fungi: An Illustrated Introduction with Keys, Glossary,
and Guide to Literature. St. Paul, Minnesota: The American Phytopathological Society.
Florian, M-L. E. (2000) ‘Aseptic technique: a goal to strive for in collection recovery of mouldy
archival materials and artifacts’, Journal of the American Institute of Conservation 39: 107-15.
Florian, M-L. E. (2002) Fungal Facts: Solving fungal problems in heritage collections. London:
Archetype Publications.
Florian, M-L. E. (1997) Heritage Eaters: Insects and Fungi in Heritage Collections. London: James
& James.
Hibbett, D. S. et al. 2007. A higher-level phylogenetic classification of the Fungi. In Mycological
Research 111: 509-547.
Larochette, Y. 2003. Mold and Museum Artifacts. An Independent Study Research Project,
Winterthur/University of Delaware Program in Art Conservation, Wilmington, Delaware.
Michalski, S. 2010. Incorrect relative humidity, in The 10 Agents of Deterioration. Canadian
Conservation Institute. http://www.cci-icc.gc.ca/crc/articles/mcpm/chap10-eng.aspx#toc
(Accessed 11/27/2011).
Nyberg, S. 2002. Invasion of the giant mold spore. Solinet preservation leaflet.
http://cool.conservation-us.org/byauth/nyberg/sport.html (Accessed 10/24/2011).
Parafilm® M. 2008. CAMEO (Conservation and Art Materials Encyclopedia Online). Museum of
Fine Arts, Boston. Online:
http://cameo.mfa.org/materials/record.asp?key=2170&subkey=6837&Search=Search&Materia
lName=parafilm&submit.x=0&submit.y=0 (Accessed 11/27/2011).
23
Taylor, John W., Joey Spatafora, and Mary Berbee. 2006. Ascomycota. Sac Fungi. Version 09
October 2006 (under construction). http://tolweb.org/Ascomycota/20521/2006.10.09 in The
Tree of Life Web Project, http://tolweb.org/ (Accessed 11/26/2011).
Spatafora, Joey. 2007. Pezizomycotina. Version 19 December 2007.
http://tolweb.org/Pezizomycotina/29296/2007.12.19 in The Tree of Life Web Project,
http://tolweb.org/ (Accessed 11/26/2011).
Sussman, A. S. (1976) ‘Activators of fungal spore germination’, in D. J. Weber and W. M. Hess
(eds) The Fungal Spore. Form and Function, pp. 101-39. New York: Wiley-Interscience.
Taylor, John W., Joey Spatafora, and Mary Berbee. 2006. Ascomycota. Sac Fungi. Version 09
October 2006 (under construction). http://tolweb.org/Ascomycota/20521/2006.10.09 in The
Tree of Life Web Project, http://tolweb.org/ (Accessed 11/26/2011).
24
APPENDIX A
GLOSSARY
Anamorph: a phase in the life cycle of a fungus where it reproduces asexually. This is
characterized by the production of conidia.
Asci (sing. Ascus): the “spore sack” of a fungus that typically contains 8 ascospores (spores
produced inside an ascus).
Ascomata: the fruiting bodies produced by certain kinds of fungi (Crous et al. 2009, 31). See
also Asci.
Chitin: composed primarily of polysaccharides, it is the primary component of the cell walls of
fungi.
Conidia: the asexual spore of an anamorph.
Dikarya: a subkingdom of Fungi. The phyla Ascomycota and Basidiomycota are grouped under
Dikarya.
Eukaryote (eukaryotic): a single-celled or multicellular organism whose cells contain a distinct
membrane-bound nucleus. This domain includes the kingdoms of plants, animals, and fungi.
Fruiting body: the visible reproductive feature of some fungi.
Fungi: Kingdom belonging to the Eukaryote domain and encompasses microorganisms such as
yeasts and molds.
Heterotrophic: a species not able to produce their own complex carbon molecules for nutrition.
Heterotrophic species rely on obtaining these from other organism. Fungi, animals and many
bacteria are heterotrophs.
Hyphae (sing. Hypha): the long, branching, threadlike elements that make up the body of a
fungus.
Meiosis: sexual reproduction characterized by cell division and formation from sex and
recombination.
Mold: microscopic fungi composed of multicellular, filamentous hyphae.
Mycelia (sing. Mycelium): a mass of hyphae.
25
Phyla (sing. Phylum): a classification category for living organisms that is below kingdom and
above class.
Phylogenetics: the study of the evolutionary development of organisms.
Sclerotia (sing. sclerotium): mass of hyphae with stored food reserves to survive inhospitable
environmental extremes
Septa (sing. septum, adj. septal): cell wall in a hypha or spore. Septate hyphae are divided into
cells by the septa.
Teleomorphs: a phase in the life cycle of a fungus where it reproduces sexually via asci and
meiosis.
26
APPENDIX B
Crista A. Pack
Preventive Conservation Research Proposal
Fall 2011
TITLE: Mold Growth and Prevention in Museum Environments
BACKGROUND RATIONALE: Conservators at the Alaska State Museum (ASM) in Juneau, Alaska recently
began a research project to study and document “white stuff” that is commonly found on objects in
heritage collections throughout the state of Alaska. The common culprits discovered included salt
efflorescences, pesticide residues, and fatty bloom. However, a few long weapons in the ASM closed
storage cabinets were discovered to have an unusual fluffy white substance which had the appearance
and characteristics of mold. These objects were comprised of wood, bone, ivory, feather, and stone; and
the white substance was found on surfaces of each type of material.
Mold was not initially a suspect on any of these objects, as the collections storage at ASM is kept close
to the desired ranges of 50% RH (± 5%) and 70° F (± 3° F). According to the Canadian Conservation
Institute’s “10 Agents of Deterioration” website:
“At 60%RH visible mould growth just possible on some surfaces, but a
stable RH at this value is rare, any intermittent period at less than 55%
will stop growth” and “[for] clean plant based organic materials: mould
rate typically requires 80% -85% RH before mould growth likely at all.
E.g., clean textiles, clean paper, clean wood.”13
Therefore, the finding of mold on ASM objects was perplexing, considering that the guidelines given to
museums indicate that mold should not grow at the lower humidity conditions maintained by the ASM.
The white substance appeared at some point while the objects were in ASM storage, because they were
noted to be in good condition without any kind of white substance on them when they came into the
collection six years ago.14 Additionally confusing was the fact that the spears are stored with other items
that do not show any white, fluffy growth.
Researching the various molds that can be found in collections environments will help museum
professionals better understand what the potential for mold growth may be in their storage and
exhibition areas. The findings of this research may also enhance the current standards for
environmental control by providing specific growth parameters for species identified in the museum
environments studied.
13
CCI, “Incorrect Relative Humidity” in Ten Agents of Deterioration. Online: http://www.cciicc.gc.ca/crc/articles/mcpm/chap10-eng.aspx. Accessed September 10, 2011.
14
From personal communication with Alaska State Museum curator Steve Hendricks and Alaska State Museum
conservator Ellen Carrlee, August 23, 2011.
27
PRIMARY RESEARCH QUESTION: Is the white substance found on ASM objects mold? And if so, what
factors contributed to its growth?
SECONDARY RESEARCH QUESTION: Why and how does mold grow in indoor environments? What are
the current recommendations for RH in museum environments based on? Do these parameters prevent
the growth of all types of mold, or just some?
RESEARCH OBJECTIVES: The primary objective is to conduct a very thorough investigation of mold by
studying the fungal spores present in two different museum environments. A second objective is to
determine the rationale behind the development of the current standards for museum environments.
The research will hopefully be useful to the Alaska State Museum and provide information that may aid
in future conservation treatments. The findings may also be helpful in identifying any modification to
the storage environment for the affected items. The final objective is to increase contacts and
relationships with experts in the field of mycology.
PROPOSED RESEARCH METHODOLOGY: The research will be conducted through a series of experiments
and a review of the available literature. The experiments will consist of attempting to grow various
forms of mold, including mold from samples sent from the ASM and samples taken at Winterthur. The
goal will be to identify what the RH and temperature limitations are for various types of mold growth
and see where these fall within the parameters outlined in conservation literature.
EXPECTED OUTCOMES: The results of this research will be analyzed with all data and conclusions
compiled into a report which will be turned in at the end of the semester. Additionally, the results may
provide answers for the Alaska State Museum and this information can be incorporated into the
museum’s weblog entitled: “Alaskan White Stuff ID.”15 The website provides information on how
identify and prevent certain kinds of “white stuff” (such as mold) commonly found on Alaskan artifacts.
TIMELINE:






September 2, 2011 – meeting with additional concentration advisor to discuss research topic
September 12 – proposed reading list with two annotations and a research proposal first draft
due by noon
September 16 – meeting with additional concentration advisor to discuss reading list,
annotations and research proposal
September 26 – research proposal due by noon
October 7 - First round of growth experiments from ASM samples and from Winterthur
environment underway
October 18 – meeting with additional concentration advisor to discuss research status,
roadblocks, successes
15
“What’s That White Stuff?: Caring for Alaskan Artifacts.” Online: http://alaskawhitestuffid.wordpress.com/.
Accessed September 11, 2011.
28





October 25 - have data assessed from first experiments and determine if further information is
needed. Begin additional experiments as needed
November 8 - meeting with additional concentration advisor to discuss research status,
roadblocks, successes
November 15 - All experiments and annotated bibliography completed
November 28 – draft report due by noon
December 16 - Final report due by 4:00 p.m.
SIGNATURES
Crista A. Pack,
Graduate Fellow, Winterthur/University of Delaware Program in Art Conservation
DATE
Dr. Joelle D. J. Wickens
Winterthur Assistant Textile Conservator and Assistant Professor
DATE
Debra Hess Norris
Henry Francis DuPont Chair of Fine Arts
Chair and Director, Art Conservation Department
Associate Dean for Graduate Education & Interim Associate Dean for the Arts
DATE
29
APPENDIX C
Annotated Bibliography
Mold Research
Fungal Growth and Physiology
Barnett, H. L. and B. B. Hunter. 1998. Illustrated Genera of Imperfect Fungi. 4th ed.
St. Paul, Minnesota: The American Phytopathological Society.
Spiral-bound, soft cover – makes for easy portability and use at a microscope.
Mainly consists of detailed drawings of various identifiable parts of fungal species.
Also provides a thorough overview of various species and definitions. A really great
guide, especially for microscope work.
Blackwell, M., R. Vilgalys, T. Y. James, and J. W. Taylor. 2009. Fungi. Eumycota:
mushrooms, sac fungi, yeast, molds, rusts, smuts, etc.. Version 10 April 2009.
http://tolweb.org/Fungi/2377/2009.04.10 in The Tree of Life Web Project,
http://tolweb.org/ (Accessed 11/26/2011).
Block, S. S. (1953) ‘Humidity requirements of mold growth’, Applied Microbiology
1: 287-93.
Cotter, D. A. (1981) ‘Spore activation’, in G. Turian and H. R. Hohl (eds) The Fungal
Spore: Morphogenetic Controls, pp. 385-411. New York: Academic Press.
Crous, P. W., G. J. M. Verkley, J. Z. Groenewald, and R. A. Samson, eds. Fungal
Biodiversity. Utrecht, The Netherlands: Fungal Biodiversity Centre.
Provides a good resource for some great images of fungi. Also provides a thorough
overview of the various species; however, some terminology seems to differ slightly
i.e. ascomata vs. asci, which has been used in other sources). Not sure if this
reflects nomenclature differences between countries, or if these various terms
reflect nuances in meaning that I’m not catching on to.
Florian, M-L. E. (2002) Fungal Facts: Solving fungal problems in heritage
collections. London: Archetype Publications.
30
Chapter 2: What are fungi? Classification and nomenclature
Intended to provide a basic vocabulary for the reader and an
introduction to the life cycle and scientific classifications of fungi. The
author also goes into the steps of identification and importance of
ensuring health and safety precautions are followed. As stated by the
author: “This chapter demonstrates that the common surface fungi
belong to a group called the conidial fungi because they reproduce
vegetatively by conidia.”
Lists four steps as essential in the event of a fungal infestation:
confine it, stop its growth, eradicate it, and prevent it from happening
again. I would think that the second and fourth are closely related. The
proposal to eradicate it seems misleading and I’m curious to see if this
discussed any further in another chapter. The decision to eradicate
mold from a heritage object could potentially cause more damage to
the object and may not always be appropriate.
Chapter 3: Where do they come from?
Discusses how mold spores find their way into collections and what
conditions are required for their growth. Emphasizes that mold is
literally everywhere and anything exposed to air will come into contact
with many various types of mold spores, but not all will develop into
mold. According to Florian: “Any material exposed to the air will be
contaminated with many different fungi, but only specific species will
develop because the moisture and other aspects of the material of the
object and the environment have met their growth requirements.”
Gives case studies.
Chapter 5: Germination and vegetative growth of fungi: why is it happening
and can we control it?
Hall, R. (1981) ‘Physiology of conidial fungi’, in G. T. Cole and B. Kendrick (eds)
Biology of Conidial Fungi, Vol. 2, pp. 417-57. New York: Academic Press.
Hibbett, D. S., M. Binder, J. F. Bischoff, M. Blackwell, P. F. Cannon, O. E. Eriksson,
S. Huhndorf, T. James, P. M. Kirk, R. Lucking, H. T. Lumbsch, F. Lutzoni, P. B.
Matheny, D. J. Mclaughlin, M. J. Powell, S. Redhead, C. L. Schoch, J. W. Spatafora,
J. A. Stalpers, R. Vilgalys, M. C. Aime, A. Aptroot, R. Bauer, D. Begerow, G. L.
Benny, L. A. Castlebury, P. W. Crous, Y. C. Dai, W. Gams, D. M. Geiser, G. W.
Griffith, C. Gueidan, D. L. Hawksworth, G. Hestmark, K. Hosaka, R. A. Humber, K.
D. Hyde, J. E. Ironside, U. Koljalg, C. P. Kurtzman, K. H. Larsson, R. Lichtwardt, J.
Longcore, J. Miadlikowska, A. Miller, J. M. Moncalvo, S. Mozley-Standridge, F.
Oberwinkler, E. Parmasto, V. Reeb, J. D. Rogers, C. Roux, L. Ryvarden, J. P.
31
Sampaio, A. Schussler, J. Sugiyama, R. G. Thorn, L. Tibell, W. A. Untereiner, C.
Walker, Z. Wang, A. Weir, M. Weiss, M. M. White, K. Winka, Y. J. Yao, N. Zhang.
2007. A higher-level phylogenetic classification of the Fungi. In Mycological
Research 111: 509-547.
A very technical look at the problem of numerous names for the same species in
the field of mycology. This article is cited numerous times in other literature,
attesting to the importance of the effort put forth by this group of scientists and
specialists to address the challenges of fungal taxonomy.
Mazur, P. (1968) ‘Survival of fungi after freezing and desiccation’, in G. C.
Ainsworth and A. S. Sussman (eds) The Fungi: An Advanced Treatise, Vol. I, pp.
269-300. London and New York: Academic Press.
Nyberg, S. 2002. Invasion of the giant mold spore. Solinet preservation leaflet.
http://cool.conservation-us.org/byauth/nyberg/sport.html (Accessed 10/24/2011).
As noted in Larochette’s (2002) annotated bibliography, the leaflet is a bit
melodramatic in the introductory paragraphs; but this is clearly written tongue-incheek and provides a bit of humor in an otherwise dry subject. Overall, it contains
information that is useful to conservators, but is geared towards a more general
museum audience.
The discussion is aimed at the effects of mold on books and paper specifically. The
author goes somewhat in-depth in giving recommendations for temperature and
humidity - stressing that they must be taken into consideration together. Also
offers some useful guidelines for what to do if you have a mold outbreak, including
remediation options.
Spatafora, Joey. 2007. Pezizomycotina. Version 19 December 2007.
http://tolweb.org/Pezizomycotina/29296/2007.12.19 in The Tree of Life Web
Project, http://tolweb.org/ (Accessed 11/26/2011).
Sussman, A. S. (1976) ‘Activators of fungal spore germination’, in D. J. Weber and
W. M. Hess (eds) The Fungal Spore. Form and Function, pp. 101-39. New York:
Wiley-Interscience.
32
Sussman, A. S. (1966) ‘Dormancy and spore germination’, in G. C. Ainsworth and
A. S. Sussman (eds) The Fungi: An Advanced Treatise, Vol. II, pp. 733-60. New
York and London: Academic Press.
Taylor, John W., Joey Spatafora, and Mary Berbee. 2006. Ascomycota. Sac Fungi.
Version 09 October 2006 (under construction).
http://tolweb.org/Ascomycota/20521/2006.10.09 in The Tree of Life Web Project,
http://tolweb.org/ (Accessed 11/26/2011).
Fungal Identification
Basset, I. J., C. W. Crompton and J. A. Parmelee (1978) An Atlas of Airborne Pollen
Grains and Common Fungus Spores of Canada. Research Branch, Canada
Department of Agriculture. Monograph No. 18 Ottawa, Ont,: Canada Department of
Agriculture.
Daffonchio, D., S. Borin, E. Zanardini, P. Abbruscato, M. Realini, C. Urzi and C.
Sorlini (2000) ‘Molecular tools applied to the study of deteriorated artworks’, in O.
Ciferri, P. Tiano and G. Mastromei (eds) Of Microbes and Art, pp. 21-38. New York:
Kluwer Academic/Plenum Publishers.
Dugan, F. M. 2006. The Identification of Fungi: An Illustrated Introduction with
Keys, Glossary, and Guide to Literature. St. Paul, Minnesota: The American
Phytopathological Society.
Spiral-bound, soft cover – makes it easy to carry around and prop open for
comparison at a microscope or other. Nice drawings and many, many definitions of
technical terms make this a very useful manual for beginners.
Florian, M-L. E. (2002) Fungal Facts: Solving fungal problems in heritage
collections. London: Archetype Publications.
Chapter 4: The culprit, conidium: what does it look like and what does it
do?
Conidia (incorrectly referred to as spores) are what land on materials
and develop into fungal colonies. Discusses their built-in survival
mechanisms and how these are important in the prevention of mold
33
growth. This may be key in discussing environmental parameters for
museums.
Fungi in Heritage Collections
Brokerhof, A. W. (1989) Control of Fungi and Insects in Objects and Collections of
Cultural Value: “State of the Art”. Amsterdam: Central Research Laboratory for
Objects of Art and Science.
Downey, A. and M. Schobert. 2000. Disaster Recovery: Salvaging works on paper.
Philadelphia: Conservation for Art and Historic Artifacts.
http://ccaha.punkave.net/uploads/media_items/technical-bulletin-salvaging-art-onpaper.original.pdf (Accessed 11/27/2011).
Florian, M-L. E. (1997) Heritage Eaters: Insects and Fungi in Heritage Collections.
London: James & James.
Florian, M-L. E. (2002) Fungal Facts: Solving fungal problems in heritage
collections. London: Archetype Publications.
Chapter 6: What’s in a fungal infestation and what is its effect on the
materials of heritage objects?
Chapter 7: Collection recovery – removing fungal structures from heritage
objects
Chapter 8: Monitoring for air quality and surface contamination in museums
and archives: a review
Chapter 9: Prevention, disaster preparedness and summary
Larochette, Y. 2003. Mold and Museum Artifacts. An Independent Study Research
Project, Winterthur/University of Delaware Program in Art Conservation,
Wilmington, Delaware.
The focus of this study was threefold: to provide an overview on how mold grows
and the mechanisms by which it can cause deterioration; to provide options (past
34
and present) for eradication; and to create a historical timeline of mold
contamination issues at Winterthur Museum, Garden, and Library–including how
these issues were handled.
Larochette’s preventive research paper provides a useful study on the various
factors surrounding mold growth. The discrepancies between authors regarding
required RH and temperature for mold growth are touched on, but not elaborated
or dealt with. The paper provides a very useful annotated bibliography that serves
as a good starting point for any research regarding mold in museums. Additionally,
the paper is thoroughly researched, organized well, and illustrated nicely. This
provided a useful resource not only for mold, but for overall organization of the final
report.
Michalski, S. 2010. Incorrect relative humidity, in The 10 Agents of Deterioration.
Canadian Conservation Institute. http://www.cciicc.gc.ca/crc/articles/mcpm/chap10-eng.aspx#toc (Accessed 11/27/2011).
Miller, D. J. and H. Holland (1981) ‘Biodeteriogenic fungi in two Canadian historic
houses subjected to different environmental controls’, International Biodeterioration
Bulletin 17(2): 39-45.
Rebrikova, N. L. and N. V. Manturovskaya (1993) ‘Studies of factors facilitating the
loss of microscopic fungal viability in the conditions of library and museum
collections’, ICOM Committee for Conservation 10th Triennial Meeting, August,
Washington, DC, Vol. II. pp. 887-90.
Street, K. N. (1977) ‘Fibre composite materials in an arctic environment’, in
Materials Engineering in the Arctic, pp. 7-10. Metals Park, OH: American Society for
Metals.
Monitoring Bioaerosols and Sampling Methods
Gallo, F. (1993) ‘Aerobiological research and problems in libraries’, Aerobiologia 9:
117-30.
35
Health Canada (1995) ‘Appendix D: Sampling methods for fungal bioaerosols and
amplifiers in cases of suspected indoor mould proliferation’, in Fungal
Contamination in Public Buildings: A Guide to Recognition and Management.
Environmental Health Directorate, health Canada, Tunney’s Pasture, Ottawa, Ont.
K1A 0L2.
Niemeier, R. T., S. K. Sivasubramani, T. Reponen and S. A. Grinshpun (2007)
‘Assessment of Fungal Contamination in Moldy Homes: Comparison of Different
Methods’, Journal of Occupational and Environmental Hygiene 3(5): 262-273.
Describes four types of methods for sampling for mold in a home. Most of it
was aimed to a very specific audience who would already have familiarity
with certain methods for testing. However, the article was useful for its
references to suppliers and specific materials used (i.e. malt extract agar).
It also provides guidelines for collection: “The surface was thoroughly
swabbed with a sterile wet swab (Fisher Scientific) to remove as much of
the mold as possible and collected in a 0.05% Tween 80 solution (Sigma
Chemicals Co., St. Louis, Mo.)” (p 264). Finally, the recommended time
period for incubation is 7 days; however, the author neglects to mention at
what temperature or any other necessary conditions for the incubation
period. Since searches for malt extract agar online mention that it is an
extremely perishable material, it doesn’t seem like leaving it on one’s desk
for 7 days would be a good idea. Overall, this may indicate that the
resource is geared to someone much more familiar with these procedures
and not a student just beginning to learn them.
Willeke, K. (1999) ‘Air sampling’, in J. Macher (ed.) Bioaerosols: Assessment and
Control, pp. 11-1 – 11-25. Cincinnati, OH: American Conference of Government
Industrial Hygienists (ACGIH).
Prevention and Environmental Control
Florian, M-L. E. (2000) ‘Aseptic technique: a goal to strive for in collection recovery
of mouldy archival materials and artifacts’, Journal of the American Institute of
Conservation 39: 107-15.
Michalski, S. (1994) ‘Relative humidity in museums, galleries and archives:
specification and control’, in Bugs, Mold and Rot II: A Workshop on Control of
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Humidity for Health, Artifacts, and Buildings, pp. 51-62. Washington, DC: National
Institute of Building Sciences.
Thomson, G. (1988) The Museum Environment, 2nd edn. Boston, Mass.:
Butterworth.
Valentin, N., R. Garcia, O. DeLuis and S. Mackawa (1998) ‘Microbial control in
archives, libraries and museums by ventilation systems’, Restaurator 19(2): 85107.
Survival of Fungi
Pathak, V. K. and S. M. Pady (1965) ‘Numbers and viability of certain airborne
fungus spores’, Mycologia 57: 300-11.
Sussman, A. S. (1966) ‘Longevity and survivability of fungi’, in G. C. Ainsworth and
A. S. Sussman (eds) The Fungi: An Advanced Treatise, Vol. II, pp. 477-86. London
and New York: Academic Press.
Additional References
American Academy of Allergy, Asthma and Immunology. NAB Scale. Online:
http://www.aaaai.org/global/nab-pollen-counts/reading-the-charts.aspx (Accessed
12/13/2011).
Parafilm® M. 2008. CAMEO (Conservation and Art Materials Encyclopedia Online).
Museum of Fine Arts, Boston. Online:
http://cameo.mfa.org/materials/record.asp?key=2170&subkey=6837&Search=Sear
ch&MaterialName=parafilm&submit.x=0&submit.y=0 (Accessed 11/27/2011).
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