Microbiology
Class Three
February 7-9
Culture Characteristics
Class schedule( Part One)
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Check results from week 2.
Record results in templates.
Organisms studied – week 2
S. marcescens
B. subtilis
M. luteus
E. coli
Culture characteristics
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Use supplement and handout to
observe the growth of the four
organisms in the slant, deep, broth, and
on the plate.
Do the organisms look like one of the
examples on your sheet?
Try to record their appearance on your
templates
Culture observations on the agar
plate
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Color production( chromogenesis). An
example of this is the pink color of
Serratia
Growth pattern and characteristics
Amount of growth( scant or heavy)
Comparison of E. coli and Micrococcus
luteus
Colony morphology
Colony morphology
Margin of the colonies
Elevation
Broth culture( refer to supplement)
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Cloudy
Turbid( Flocculent)
Sediment formation
Pellicle formation
Slants
Is there growth in the
bottom ?
 Is there growth on the
slant itself
 What are the growth
characteristics on the
slant?
 Key words
Aerobic
Anaerobic
Facultative
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Isolation of Pure culture
Observe your dilution streak of your mixed
culture
 On the bottom of your Petri dish circle colonies
of two organisms
 Example
ML/SM mixture – circle yellow and pink cultures
 With your inoculating loop lift cells from circled
colonies and streak on new plate or inoculate a
slant per detailed instructions in class
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Part One – Completion of week 2
work
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When you have finished observing all
of your cultures
Place all tubes in rack in hazardous
waste
Place all plates in cans in hazardous
waste
Wipe down desk top
New work( supply table)
Eight Organisms for Study/Table
 8 Plates
 8 Deeps( if available)
 8 Slants
 8 Broths
Preparation
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Label all tubes and plates carefully
Assign each member of the group 2
organisms
Transfer the organisms to the culture
media using aseptic techniques used in
weeks one and two
Organisms for study
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Gram negative organisms
PA - Pseudomonas aeruginosa
PV- Proteus vulgaris
EC- Escherichia coli
EA- Enterobacter aerogenes
Gram Positive Organisms
BS - Bacillus subtilis
SA - Staphylococcus aureus
SE - Staphylococcus epidermidis
SS- Streptococcus salivarius
Review for Quiz One
1.
2.
3.
4.
5.
Aseptic techniques
Culture transfer techniques
Media
Safety precautions
Microscope identification