Microbial
Biodeterioration of
Material and it’s Control
Arish Daud
Musawer Ali
Sagheer Ahmed
Anil Yousaf Masih
Danish Gul
Biodeterioration
• Bio-life
• Deterioration- destruction, impairment
• H. J. Hueck gave the first definition in a paper in 1965:
• “any undesirable change in the properties of a
material caused by the vital activities of an
organism”
• Text book defines it as “any undesirable change
occurring in a natural or processed material of economic
importance, brought about by the activities of living
organisms whether plants, animals or, microorganisms”
Natural
Material
Processed
Material
• Animal products (bone, fur etc.)
• Plant products (wood, cotton
etc.)
• Stored unprocessed foodstuffs
(grain, potatoes, fruits etc.)
• Stone
• Building materials (brick,
concrete and mortar)
• Cellulosic materials (chipboard,
paper and card)
• Petrochemical products (fuels
and lubricants),
• Glass,
• Metals,
• Paints
• Pharmaceuticals,
• Cosmetics and toiletries,
• Other products such as
microchips.
Biodeterioration vs.
Biodegradation
• Biodegradation is also impairing things by living
organisms, so does that mean both terms have same
meaning?
NO!
• Biodegradation• positive aspects of microbial activities
• Biodeterioration
• negative aspects of microbial activities
• Depends on the location of microbial activity
Biodegradation
Biodeterioration
Fallen tree decaying
Wet Rot decaying ceiling
Biodeterioration
of solid materials
• Biodeterioration of
solid materials starts
with formation
of a biofilm
Factors that cause Damage
Mechanical/Physical Damage
• Fungal hyphae growing through walls
• Microbial mass causing breakage of pipes
Chemical/Biochemical Processes Damage
• Utilizing the material as a carbon or energy source
Soiling/Fouling
• Aka aesthetic biodeterioration
• Simply present on a surface,
• feeding on the top layer
• Do not cause physical damage
Biodeterioration Cont…
• Biodeteriogenesis functions like a disease
• Has three phases:
• Infection/Contamination
• Incubation
• Manifestation (Symptoms start appearing)
• Economic aspects
• Cost of prevention (physical-cooling or chemicalpreservatives etc.)
• Material replacement
• Restoration
Biodeterioration of Stored
Plant Food Material
Anil Yousaf Masih
Non Food Animal Products
Sagheer Ahmad Malik
Non Food Animal
Products
•Hides(animal skin treated for human use)
•Leather
•Stone and related building materials
•Cellulosic materials
Leather
• Contain fatty and proteinaceous debris
• Could be degraded by proteolytic and lipolytic enzymes by
micro-organisms
• To avoid this biocides are used
Steps for leather production
•
Soaking in water
Susceptible to attack by bacteria B. subtilis etc
Enzyme are secreted at this stage.
Active even after the death of micro-organisms
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Liming, deliming and then tanning
Drying
80% humidity favours micro-organisms growth
Fungi is primary biodeteriogens
Bacteria are usually secondary colonizers
Wool, fur and feathers
• composed of cystine-rich protein keratin
• Losses are because of keratinophilic fungi and certain bacteria
• The damages are pigmentation, odour production and loss of
tensile strength
• incorporation of biocides during processing prevents from the
problem
Stone and related building
materials
• prone to microbial attack mainly Algae, cyanobacteria, fungi
or lichens.
• Causes soiling, excessive expansion, widening of cracks
• excretion of corrosive metabolites
• Several organic acids solubilize calcium carbonate
• oxalic and citric acid solubilize
• silicates
Continue
• Nitrifying bacteria, may also cause damage by solubilizing
calcium-based rock, as their oxidation of ammonia to nitrate
leads to the formation of a relatively soluble salt, calcium
nitrate.
• Problems can be handled by frequent painting, or cleaning
with biocidal washes of bleach, phenolics.
Cellulosic materials
wood, card,
paper and plant fiber textiles
• susceptible to fungal attack, some bacteria, notably
Cellulomonas and Cellvibrio specie.
• Enzymes are cellulase, a complex of several enzymes including
exo-b-1,4-glucanase, endo-b-1,4-glucanase and b-glucosidase,
and hemicellulases
• Damage ranges from loss of quality to major reductions in
strength.
• They do not spread beyond the damp areas and are far easier
to treat by biocides
Degradation of
Metals
Musawar Ali
Degradation of Metals
There are three main routes of microbial corrosion of metals.
1. Concentration of cells
2. Release of corrosive metabolic products
3. Removal of cathodic hydrogen by sulphate reducing bacteria
Microbial concentration cells
• As a result of oxygen gradient
• Microbes on borders have access to more oxygen so they
become cathodic
• Oxygen limited centre becomes anodic
• Metal in the oxygen deficient portion loses electrons and
becomes positively charged and reacts with OH- ions to form
insoluble metal hydroxide.
Corrosive metabolic products
• Microorganisms produce organic and inorganic acids cause
metal corrosion
• examples:
• Sulphur oxidizers produce highly corrosive sulphuric acid
which degrades fuel tanks.
• Sulphate reducing bacteria produce hydrogen sulphide
which can cause sulphide stress cracking.
Susceptible alloys, especially steels, react with hydrogen
sulfide, forming metal sulfides and atomic hydrogen as a
result of corrosion.
Plastic degradation
• Plastics are polymeric materials that include
polyethylenes, polystyrene, polyvinylchloride
and polyesters.
• Plastic material are largely resistant to microbial
attack but the other materials added to the
plastic are suseptible to microbial attack.
• initially the microbes metabolize these additives
and form a surface biofilm as a result of which
plastic becomes fragile and discolored.
Arish Daud
Pharmaceutical product classification
•Non-sterile: solids (tablets, capsules and
powders),
liquids (suspensions and syrups), creams
and lotions;
• Sterile: injectables (parenterals), both
single dose and multidose drugs,
intravenous infusions, etc., along with
products for use in and around the eye area,
including drops, lotions, ointment, washes
and contact lens cleaning solutions.
•The presence of low levels of acutely
pathogenic microorganisms or higher levels
of opportunistic pathogens.
•Contamination with toxic microbial
metabolites that can persist even when the
producer microorganisms are
dead or removed.
•The occurrence of detectable physical
and/or chemical changes.
• Loss of function of the active
ingredient(s).
•Chemical and physicochemical changes
•Oils and fats are particularly susceptible to
microbial attack
•Loss of function of the active ingredient
•The active ingredient is often present at
relatively low Concentrations
•Active ingredient may be therapeutic or
antimicrobial agents, and in cosmetics and
toiletries they are mostlydetergents,coloring
agents
•Bacterial species attack the detergent in
cosmetics and toileteries are Pseudomonas,
Citrobacter and Aerobacter species
•Factors influencing microbial spoilage
•Microbial growth is determined by
nutrient status of the product formulation,
pH, oxygen concentration, water activity,
temperature and the efficacy of the oxygen
concentration of the preservative system
employed
•Moisture content of a product
•Redox potential, the oxidation–reduction
balance
•The pH of a product obviously influences
the range of microorganisms that will grow
•Package design also influences the
susceptibility of a product to
Biodeterioration
Assessment of microbial contamination
(microbiological quality control)
Microbial quality control is conducted
to:
• monitor microbial contamination of raw
materials;
• monitor and confirm the efficacy of
operations such as sterilization;
• control the danger from pathogenic
microorganisms by confirming their
absence
• Verify the expected storage life and
provide an estimate of perishability
•Sensitive analytical tests are available for
the detection of very low levels of
mycotoxins.
moebocyte lysate assay
•Very sensitive and can detect as little as 1012 g/ml.
•Detection of microbial enzymes
is often important
•Other tests that may be performed on the
products are ‘challenge tests’
Pseudomonas aeruginosa
(Gram-negative), Staphylococcus
aureus (Gram-positive), Candida albicans
(yeast)
and Aspergillus niger (filamentous fungus)
Preservatives
• Chemicals or substances that preserves or protects the
substance added to.
• Aim of using preservatives:
• Kill or inhibit growth of microbes
• Which one to add?
• The least toxic that will do the Job!
• How much to add?
• As little as possible
BUT! Don’t
• Underdose-could cause development of resistance
• Overdose- less economical, and could be toxic
What’s a good preservative like?
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Broad Spectrum
Free from toxicity, irritancy and allergenicity,
Stable,
Compatible with all other formulation ingredients
Free from odor and flavor.
Has no effect on chemical or physical properties of the
product.
Cont…
• Final Choice of Preservative for a substance depends on:
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Activity spectrum
Solubility
Stability
Volatility
Toxicity
Color,
Odor,
Irritancy,
Taste,
And especially pH:
• Preservatives have a small range of pH to work on.
Availability of Preservative in the
Product
• Not all the preservative present in the product is
available for the “preservation”
• The unavailable preservative could exhibit
allergenecity or toxicity.
• Multiple factors for this unavailability
• Basic factor
• Most of the Cosmetic products are multiphase
systems
• Are in the form of emulsions
Adsorbed to
Closure and
Container
Total
Preservative
Interacts with
formulation
ingredient
Inactive pH
effect, etc.
Aqueous
phase
preservative
Degraded
Adsorbed to
solid particulate
material
Partition into oil
phase
“Active
available
preservative
Preservatives for Cosmetics and
Pharmaceuticals
Some of the Preservatives are:
• Alcohols
• Widely used disinfectant and antiseptic
• Ineffective against endospores
• 50-70% ethanol denatures proteins and solubilize lipids
• Formaldehyde
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Highly reactive
Reacts with NH2, SH and COOH group
Possibly carcinogenic
Formaldehyde donors, like Germall 115-imidazolidinyl urea now
preferred
• Less carcinogenic
Cont…
• Quaternary Ammonium Cpds.
• Surfactants
• Skin antiseptics and disinfectants
• Preservative for ophthalmic preparations, like eye drops, contact
lens solutions
• Activity enhanced by EDTA
• Less active in presence of organic cpds.
• Silver nitrate
• General antiseptic
• Used in pharmaceutical products for the eyes
When different preservatives are mixed up…!
• Great benefits have been gained:
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Increase in activity spectrum
Reduced irritancy and toxicity (low level of each is used)
Decreased chance of development of resistant microorganisms
Synergistic preservative effects
Prolongation of preservative action
Compensation for physicochemical limitations.
Biodeterioration Testing
• Testing of materials for resistance to biodeterioration and also
testing for the efficacy of biocidal treatments
• Two ways to do it:
• Soil Burial tests
• Material is buried in the soil for some time,
• Later removed and checked for changes in color, tensile strength,
loss of mass etc.
OR
• Specifically challenged with a known biodeteriogen:
• Provide favorable conditions like pH, temperature, humidity etc.
• After some period of incubation test the material for changes and
loss in different properties.