1. Microbiology Lab review

2. Lab 7
• Cardinal temperatures
Composed of a minimum a maximum and a
optimum.
Example.
Psychrophile min -15C, optimum 0C, maximum
12.5C
Mesophile min 12.5C, optimum 37C,maximum 45C
Pathogens optiumum 37C Reason human body
temperature.

3. Lab 7
• Oxygen requirements
We tested these by using thylogylcolate tubes on the top
theses tubes were pink this was showing us the present
of oxygen
Organism that grew throughout were the Aerotolerant
anerobes
Organism that grew at the top the most and through out
the broth were the Facultative anerobies.
Only at the top were the anerobes
Make sure you know each type of organism, and the
enzymes they posess( catalase, and SOD) and why this
is important.

4. Lab 7 oxygen requirements

5. Examples of tubes

6. Lab 8
• Broths
• Sucrose if the organism turns the broth yellow
it has the ability to break down sucrose
• Dextrose if the organism is able to break down
dextrose it can break down glucose.
• Durham tube traps CO2 if the organism is able
to ferment either sugar it will make CO2 which
the Durham tube will capture.

7. Examples

8. Lab 8
• TSI( Triple sugar iron)
• In this medium 3 sugars are in it including sucrose
lactose and glucose. Glucose is in a lower amount so if
glucose is utilize it will produce a lower amount of acid
since this is a slant Oxygen will oxidizes the glucose so
only the bottom will be yellow. If sucrose or lactose is
utilize the entire tube will be yellow. If Iron is also
incorporated so if the solution changes to black it
means H2S are being produced from the break down of
peptones. The H2S is reacting with FeSO4 producing
the Black.

9. Example

10. Lab 9
• Sim ( sulfur indole motility)
• This is a Semi-solid medium that has the indicator molecule
Fe(NH4)SO4, this molecule will react when H2S is produced
from the break down of cystine . This tells us that the
organism utilizes a enzyme called cystine desulfurase.
When a organism possess a enzyme called tryptophanase
this breakes down tryptophan into a molecule called indole
and ammonium. We used the kovac’s reagent to test for
this molecule. If it is red on top it means that it possesses
tryptaphanase.
• Motility this is present when we see that the organism has
moved throughout the tube.

11. Example

12. Lab 9
• Simmons citrate this is a synthetic medium. This
medium has the PH indicator of bromothymole
blue. This will change from a green to a blue
when the organism breaks down citrate into O2.
The sodium in the medium will react with citrate
producing sodium carbonate this is a basic
product changing the medium blue. This tells us
that the organism has the enzyme citrate
permease. This is also a slant this is because it
requires O2 to be present to oxidize citrate.

13. Example

14. Lab 9
• MRVP Methyl red Voges-Proskauer
• The Methyl red is a PH indicator that will change
the medium only if the organism produces a
lower PH than 4. Phenol red was 6.4-6.3. this is
used because This organism is a mix acid
fermented. VP utilizes barrits reagent to test for
acetoin. This tells us if the organism has the
pathway of the 2-3 butanediol.
• Positive for MR is yellow
• VP is red on the top Yellow on the bottom.

15. Example

16. Lab 10 Enzymes
• All the enzymes in this lab (except catalase) are
exoenzymes.
• Cellulase This is a molecule that hydorlyzes
cellulose to glucose. This will have a zone around
it. Tells us if the organism possess the enzyme
cellulase. Uses Congo red to stain the agar and
counter stain with NaCl.
• Starch medium this has this is the same in that
there will be a zone that is positive. Tells us if the
organism possess alpha- amylase. Will use grams
iodine to stain the agar.

17. Examples

18. Lab 9
• Gelatinase
• This is a media that does not contain agar
instead it has gelatin. Gelatin is boiled collagen
and connective tissue. If a organism is able to
break this down it tells us that this organism has
this virulence factor . This tells us if the organism
is able to break down our tissues and get deeper
into our tissue. A positive test will be liquid after
20min in ice if solid the organism doesn’t posses
gelatinase.

19. Example

20. Lab 9
• Catalase this is a to test if the organism is able
to break down h202 into h20 and o2 the
presence of bubbles indicates this.

21. Example

22. Lab 11
• Antibiotics
• Know zone of inhibition
• Can not compare the zone of inhibition to two
different antibiotics because of molecular weight.
• Can only compare same antibiotic and different
bacteria to see how effective the antibiotic is.
• Gram positive and gram negative antibiotics differ
in the cell wall since gram positives have a larger
peptinoglycan they are more reliant on that wall
then gram -.

23. Example

24. Lab 11
• Physical
• UV light unionizing
• Will make thymine dimer can kill the cell. Will
mutate a lot of times.
Gamma radiation / x-rays ionizing rays
This will sheer DNA destroying it killing the cell.
can mutated it.