Enhancement of Analytical
Thinking through Scientific
Investigations
Lesson 8
Instructor: Ann S N Lau
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Microorganisms
http://www.thinkgeek.com/geektoys/plush/6708/zoom/
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Microorganisms
 The oldest form of life on earth
 Sometimes called “microbes”, especially the
disease-causing species
 Small in size, barely be seen by naked eyes,
requires the use of microscope for investigation
 Found in environment, food, industrial, medical;
beneficial or harmful
 Unicellular or multicellular
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Microorganisms
Living requirement
Water
Substratum (sometimes)
Nutrient (they recycle nutrient by acting
as decomposers)
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Classification
 Unicellular or multicellular
Examples Bacteria (unicellular)
Fungi (e.g. yeast) (unicellular or
multicellular)
Protist (e.g. one-celled algae: diatom, slimemold, etc.)
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Bacteria
 E.coli, Bacillus, Cynobacteria (Photosynthetic),
Streptococcus 鏈球菌 , Staphylococcus 葡萄球菌
 Small in size (micrometers 10-6)
Staphylococcus
http://en.wikipedia.org/wiki/Microorganism
 Can grow anywhere, reproduce by binary fission or budding
 Cell wall, lack of organelles, no define nucleus
Cynobacteria
http://en.wikipedia.org/wiki/Bacteria
E.coli
http://en.wikipedia.org/wiki/Microorganism
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Fungus
 Saccharomyces cerevisiae,
http://en.wikipedia.org/wiki/Aspergillus
Candida species, Penicillium, Aspergillus species (bread
mold), mold species that cause athletes foot etc.
 Can be beneficial or harmful
 Use in food industry, but some species can cause food
to deteriorate
Aspergillus niger
Candida albicans
http://en.wikipedia.org/wiki/Yeast
http://en.wikipedia.org/wiki/Aspergillus
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Protist
 Slime mold, diatom 矽藻
 May be able to have slight movement
http://en.wikipedia.org/wiki/Slime_mold
http://en.wikipedia.org/wiki/Diatoms
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Microorganisms
Environment
Bacteria – nitrogen cycle and carbon cycle
Waste water treatment
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Microorganisms
Food industry
Xylitol crystal
http://en.wikipedia.org/wiki/Xylitol
Alcoholic beverage (wine fermentation),
soda, root beer, bread baking, xylitol
production
Probiotic supplement 益生菌
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Microorganisms
Biotechnology
Short life-cycle with simple genome
Good study model in biotechnology
Used in gene cloning, recombinant protein
and DNA technology
Production of insulin, growth hormone, etc.
Genetics studies
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Microorganisms
Beneficial
or
Harmful
??
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Microorganisms
Beneficial
Food production
Antibiotics production
Alcoholic fermentation
Bakery
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Microorganisms
Pathogenic 致病的
cholera 霍亂
syphilis 梅毒
anthrax 炭疽
leprosy 痲瘋
tuberculosis 結核病
Plaque (Black Death)
Normally cause infection
Anthrax
http://en.wikipedia.org/wiki/Bacteria
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Microorganisms
Disease
Infection
Food deterioration
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Experiment and assignment !!!
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Sampling of microorganisms
Materials:
Different kinds of Bread
Conditions:
How to “culture” the samples?
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Strategy
Different types of bread / Why?
Living conditions or how to culture / How?
What do you want to sample / What?
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Bread Mold
http://encarta.msn.com/media_461516551/Black_Bread_Mold.html
http://www.garden.com.hk/web/en_product.php?id=13&language=en
http://www.glad.com.au/gladProducts/foodDetails.asp?pId=12
How to make use your bread?
 Cut it into equal size? Use as original size?
 Record the nature of the bread used?
 Sampling area – should we sample dirty area or
clean area? Or both?
 Any control experiment required? What kind of
“Control”?
 Method of sampling: basically by contact or
swabbing (How hard should I swab?)
 What kind of microorganisms are expected to
be collected?
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Diagram showing cultivated microbes
http://www.ars.usda.gov/is/AR/archive/oct05/air1005.htm
http://www.biofilmsonline.com/cgi-bin/biofilmsonline/ed_drop_plate_methodA.html
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Condition 1
Zip bag
Nature of the bread: (Brand name, characteristics, or you
can do a summary table as a key underneath)
Sampling area:
Method of sampling:
Bread
Any moisture added?
How long did it take to have the first lawn of
microorganism appears?
Any moisture added into the bag before culturing?
Observation:
Type(s) of microorganism appear(s ) onto the day:
Condition 2
Zip bag
Nature of the bread: (Brand name, characteristics, or you
can do a summary table as a key underneath)
Sampling area:
Bread
Method of sampling:
Any moisture added?
How long did it take to have the first lawn of
microorganism appears?
Any moisture added into the bag before culturing?
Observation:
Type(s) of microorganism appear(s ) onto the day:
Zip bag
Zip bag
Bread
Bread
<Both samples were from area 1>
Consider different sample treatment being collected in the same way? (e.g. under sunlight, in
refrigerator, in a moist / damp area, etc.)
A
B
Zip bag
Zip bag
Bread
A from area 1 and B from area 2
Both treated in the same way but sampled from different areas?
Bread
Assignment – Submit a proposal
 A comprehensive record of your experiment (method
/ strategy)
 A complete record of your result
e.g. What kind of microorganism you have collected?
Matching it with reference book / internet source?
Comparisons of your result with different sampling
and treatment method?
 Take photos if necessary
 Organize your method and result in a report format
 Each group submit one report and a short
PowerPoint Presentation (5 minutes, 10-15 slides)
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How mold looks like?
Start up of mold development on culturing medium
Well-developed mold in the same medium
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Where does mold grow?
http://www.moldinspector.com/mold_photo.htm
Bread mold
http://encarta.msn.com/media_461516551/Bla
ck_Bread_Mold.html
http://www.nimr.mrc.ac.uk/news/2006/wellcome_img/mould/
Credit: Liz Smith / Wellcome Images
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Other microorganisms……
Candida albicans (yeast)
Listeria monocytogenes (bacteria)
MRSA (Methicillin-resistant Staphylococcus
aureus)
抗藥性金黃色葡萄球菌
E.coli O157
Salmonella 沙門氏菌
http://www.bd.com
http://www.oxoid.com
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