Microbiology Lab Report - Bacterial culture characteristics and Streak plate Method

LAB REPORT 4 –
Selected questions from Exercises 2-2, 2-3, & 2-4 and 1-5 (Bacterial culture characteristics
and Streak plate Methof of isolation & demonstration of pour plate) and
example of table for your results for pigmentation (see Table below)
Note: This lab report is turned
in after you have viewed the results for Exercise on culture and growth
characteristics (done as a demonstration) and streak plating, etc.. . This lab report has 2 parts. .
When turning in the lab, make sure you include information relevant for BOTH parts. For Exercise 1-5,
you may be working as a team to be preparing streak plates and will observe
the professor perform a pour plate method for isolating colonies. You are responsible for making observations
about both the pour plates and streak plates.
For Exercise 2-2,2-3 & 2-4 which is done as a demonstration, questions
will be provided alongside the demonstration cultures to help you make
appropriate observations. Some
additional information may be e-mailed to you.
Some
of the bacteria for these exercises are usually: E. coli, Serratia marcescens, Micrococcus luteus, Bacillus subtilis,
Pseudomonas fluorescens (or
P.aeruginosa), Mycobacterium phlei (or
M. smegmatis) and sometimes S. aureus. If M. smegmatis and/or P. aeruginosa is
used, there will be added explanation.

Exercise
1-4 results: Draw your results for your
streak plate and the demonstrated pour plate and/or provide a good description ( if necessary, describe your class mates
streak plate and potentially explain what went wrong with yours). The considerations mentioned in point 2 and 3
under results and interpretations on p. 33-4 should be helpful. Among
the issues that should be addressed: Did you get isolated colony forming units
(aka colonies)? If not, why do you think you were not able to?

Growth/culture
characteristics exercise results: FILL IN information for Pigmentation Table below

N.B. These next questions are
not identical to the ones provided during the lab session but answering those
questions during lab should help you in answering these questions (which help
prepare you for lab exam, etc.)
a)In broth, does M. phlei
grows in suspension, i.e. does it cause the broth to become turbid throughout
the entire tube? Do the colonies on
solid media look flat like other colonies? Explain your answer.
This somewhat relates to term
in matching exercise below, friable.
b) Are all colony forming
units (CFUs) transparent? Which are not?
c)Which CFUs have irregular
edges (wispy edges) suggesting that the bacteria might be motile? This
relates to terms below in matching (filiform colonies vs. colonies with
spreading edges).
d)Which bacteria that we
observed do not produce pigment?

In
discussion, include answers to:
Q1.
How does complex medium compare to
synthetic (chemically defined) media?
What kind of medium were you using in the exercises such as the staining
exercise and the streak plate/pour plate exercise?
Q2.
What is the meaning of the term colony forming unit (CFU)? Why is it applicable when talking about the
growth on a streak plate? Is a CFU
always an indication of a pure culture?
Q3.
Define or explain:
a) obligate anaerobe
b) facultative anaerobe
Q4.
What is the purpose of inverting inoculated plates during incubation?
Q5.
Match the following terms from exercise 2-3 in lab manual usually in use
______
filiform 1. Produces
colored growth
_____
_spreading edge 2. Smooth texture with solid edge
______
transparent 3. Solid
growth seeming to radiate outward
______friable 4. Almost invisible
or easy to see light through
______pigmented 5. Rough texture with a
crusty appearance
Q6.
Match the following terms from exercise 2-4 in lab manual usually in use
_____Flocculent a. Evenly cloudy
throughout
_____Sediment b. Growth at top around
the edge
_____Ring c. Growth at the
bottom
_____Pellicle d. Membrane at the
top
_____Uniform
fine turbidity e. Suspended chunks or
pieces

Note for lab exam: Should
have understanding of i) why is agar added to media ii)besides pigment production, possible other
culture characteristics that can be useful in identifying a bacterial species
(photos
in handouts, etc. can be very helpful here) iii)what reasons might lead to
absence of growth on a streak plate. You
should know what the term pure culture means.
And you should have an idea as to meaning of the concept of aseptic
technique, why it is important, how we do this in the lab, etc.

Last Completed Projects

topic title	academic level	Writer	delivered