Biology 220 Microbiology
Kathleen Devlin
kdevlin@csusb.edu
General Lab Info
Midterm – 100 pts
 Lab Final – 100 pts
 Lab Assignments – 32 pts
 Lab
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This may include
• weekly in-lab assignments
• quizzes
 Lab
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Participation – 18 pts
1 pt each week for signing in on time
1 pt each week for proper cleanup
Lab Protocols
 Be
on time
 Read your lab prior to lab
 Clean up after yourselves
Biohazard Disposal
 Put
tubes in tube rack
 Put plates, pipet tips, microtubes, etc in
biohazard bucket
 Put dirty slides in “Dirty Slides” bucket
 Put broken glass in “Broken Glass” bucket
Lab Safety
 No
food or drinks
 Clean your lab bench with disinfectant
before and after lab
 Report any broken glass or injuries
immediately
 Be aware when using bunsen burners
Exercise 1 - Scavenger Hunt
 Objective:
lab
Find items commonly used in
Exercise 2 – The Unseen
Organism
 Bacteria
and some Fungi are too small to
be seen, but are everywhere (ubiquitous)
 Objective: Demonstrate that
microorganisms exist in the air and on
surfaces
Types of Cultures/Media
– liquid
 Slant – solid, agar containing tube, dried at
an angle
 Plate – solid, agar containing petri dish
 Broth
 We
will use many types of media
throughout the quarter, each having
different nutrients/properties
Aseptic Transfers
 Movement
of bacteria from one media
culture to another, without introducing
contamination
 Tools
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Loop
Needle
Flame
Sharpie (label everything!!!)
Aseptic Transfer, cont.

Label the new, sterile media (initials and bacteria being
transferred)

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Label tube glass or bottom of plates
Hold both tubes in hand not holding inoculating
loop/needle
Flame inoculating loop/needle until red hot
Cool ~15 seconds
Remove both caps with little finger
Pass tube opening through flame
Take inoculum from tube and quickly place in/on new
medium
Flame tube openings
Recap
Exercise 3 - Culture Transfer
Techniques

Objective: Transfer a bacterium from a culture to
sterile media without introducing contamination
 Each group of 4 students will need:


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2 broth tube
2 slant tube
2 agar plate
Transfer Micrococcus luteus broth to each type
of media
 Transfer Micrococcus luteus slant to each type
of media
 Place tubes in incubation rack and plates in tub
(always incubate plates upside down!!!!)
Microscopy
Microscope Care
 Make
sure lenses are clean (w/lens paper)
 Store with lowest power objective lens in
position
 Stage should be all the way down
 Turn power off
Tips for Using the Microscope
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Always start on the lowest power (4x)
Use course focus to bring object into view
Use fine focus to make the image sharp
Move to the next power
Use only the fine focus from here on out
Before you get to the 100x lens, put a drop of oil
on the slide
Use the iris diaphram and light intensity to adjust
light levels
Exercise 4 – ID of Cells

Objectives: Recognize visual differences
between prokaryotic and eukaryotic cells;
Identify three basic morphologies of prokaryotic
cells.
 Eukaryotic – cells of animals, plants, fungi, and
protists. Contain membrane bound organelles
 Prokaryotic – cells of bacteria. No membrane
bound organelles. 3 basic shapes
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Cocci = sphere
Bacilli = rod
Spirilla = spiral
Staphylococcus aureus

Gram-positive, cluster
forming (like grapes)
cocci
 Normally found in
nose and on skin
 Can cause
pneumonia,
nosocomial infections,
food poisoning, TSS
Bacillus cereus

Gram-positive rod
 Causes
gastrointestinal
intoxication
 Found in a wide
variety of foods
Treponema pallidum

Spirochaete
bacterium
 Causes syphilis
Yeast
 Eukaryotic
 Fungus
 Used
in making beer, wine, and cheese
 Can form symbiotic relationship with
bacteria
 Note:
These cells are round, but we do not
use the term “cocci” for eukaryotic cells.
Human Blood Smear
 Eukaryotic
 Note:
cell
These cells are round, but we do not
use the term “cocci” for eukaryotic cells.
Note the size difference between
prokaryotic and eukaryotic cells
Exercise 5 - Motility
 Objective:
Determine if a bacterium is
motile
 Some bacteria have the ability to move
toward or away from a stimulus
 TTC will turn red along the path traveled
by the bacterium