Lecture 21:
Identification of Bacterial Unknowns IV
I. The MR/VP test is used to differentiate between ________________________
________________________ organisms based on the way they ______________
___________________.
Organisms can usually only be _______________________________________.
However, organisms can be MR-, VP-.
Examples:
Escherichia coli is ___________________.
Enterobacter aerogenes is ________
and VP+.
Pseudomonas aeruginosa is MR- and __________.
II. Simmon’s Citrate Agar
A. This is a ____________________________________
used to determine if an organism can use citrate as its ________________________________.
It is often used to _____________________________________________
_________________________________.
B. In citrate-positive organisms, the enzyme ______________________
hydrolyzes citrate into oxaloacetic acid and acetic acid. The oxaloacetic
acid is then hydrolyzed into pyruvic acid and ____________.
D. If CO2 is produced, it reacts with components of the medium
to produce an _______________________________________
(e.g. Na2CO3). The alkaline pH turns the ____________________________________________
from __________________________________.
This is a _____________________
result.
E. Escherichia coli and Shigella dysenteriae are ___________________
whereas Klebsiella pneumoniae and Proteus mirabilis are ___________________.
See
Summary of Biochemical Tests (Simmon’s Citrate Agar)
III. Spirit Blue agar
A. This agar is used to identify organisms that are capable
of producing the enzyme ___________________.
This enzyme is secreted and _______________________________________
to ___________________ and three
____________________________________________.
These compounds are ___________________________________
to pass through the bacterial cell wall.
1.) Glycerol can be converted into a ______________________
__________________________.
2.) The fatty acids can be ____________________________
and their fragments can eventually enter the ___________________
______________________.
B. Spirit blue agar contains an emulsion of _________________________
___________________________. Bacteria that produce lipase will
hydrolyze the olive oil and produce a ______________
around the bacterial growth.
See
Summary of Biochemical Tests (Spirit Blue Agar)
C. Bacillus subtilis is lipase ____________________.
IV. Starch hydrolysis test
A. This test is used to identify bacteria that can ______________________
_____________________________________________ using the enzymes
________________________ and oligo-1,6-glucosidase.
B. Often used to differentiate species from the genera _________________
__________________________________.
C. Because of the _______________________________
of amylose and amylopectin molecules, these starches ______________________________
through the bacterial cell wall.
1.) In order to use these starches as a carbon source, bacteria must _____________________
a-amylase and oligo-1,6-glucosidase into
the extracellular space.
2.) These enzymes ________________________________________
______________________________________ subunits which can
then be utilized directly as carbon sources.
D. After incubation of the starch plates, _____________________
is added to the top of the agar. The iodine reacts with the starch to form
a ____________________________________.
Hydrolysis of the starch will ___________________________________________________around
the bacterial growth.
See Summary
of Biochemical Tests (Starch Hydrolysis Test)
E. Bacillus subtilis is amylase ___________________.
ALSO TODAY:
*Perform ____________________________________
needed to help determine your unknown: oxidase, catalase, various stains.
*Determine your unknown and _______________________________________
____________________________ ______.
*Papers - Consult the lab notebook for a description of the report format.
If you have any questions about the report be sure to ask today.
* Remember the late policy: _____________________________________
that a report is late. Late reports are not accepted after 1 week.
* Reports are due on ___________________!
*Make sure that once you have correctly identified your unknown, you discard
all your plates and slants in the biohazard, tape in the trash, and wash all
the slides.
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