1. Liquid _________________________
2. Solid _______________
- made from rhodophyte or red algae.
B. Defined vs. undefined (complex) media
1. A ________________ medium
is made by weighing out every potential nutrient component carefully (i.e.
glucose, ammonium sulfate etc...). Advantages: we know __________________________________,
and therefore it is useful in determining ______________________
___________________________of a particular organism. Disadvantages: _____________________,complicated preparation.
EXAMPLE: Glucose Salts Agar (GSA)
2. An ______________________,
or complex medium is prepared with complex natural extracts and digests
of ___________________ _____________________________________. Advantages: easy preparation, inexpensive. Disadvantages: cannot be used to define precise growth
____________________________ because we don’t
know exactly what’s in it.
EXAMPLE: Trypticase Soy Agar
C. Selective vs. Differential
1. Selective means that the medium can _____________________
______________________________by _____________________
the growth of others. 2. Differential media are designed to tell us the ________________
_________________________ growing on the same culture medium.
These media generally contain some kind of chemical that is altered in
a visible way by some bacteria but not others.
Example: Eosin Methylene Blue (EMB) is both selective and differential.
III. Quantization of bacteria
A. This is an attempt to determine the number of bacteria/mL in a culture.
This can be done either directly or indirectly.
1. DIRECT
a. ___________________________:
This means one actually counts each bacterial cell on a microscope slide. Disadvantages: This takes a great deal of time and we ______
__________________________________________________. Advantage: No overnight incubation is required.
b. The ____________________________________________
(SPC) method.
1.)A ________________________________________
____________________. Set aliquots of the final, dilute
solution are spread on agar plates.
2.)Every cell that was spread onto the plate develops into
a _________________________________.
These colonies can be counted and since they originated from a single
cell they ________________________________
_______________________________ that was spread onto
the plate.
3.) The dilutions made from the original culture can then be taken
into account and one can _________________
__________________ to determine the _____________
__________________ of the original culture. Disadvantages: aggregates of bacteria will form ______
___________________ if not well dispersed. Results
are not immediate; you have to wait a day or two. Advantages: only counts _________________________
__________________________; can measure really low
concentrations; doesn’t require lots of instrumentation or training.
2. INDIRECT
a. Spectrophotometer – measures _______________________. b. Measurement of __________________________________. c. Measurement of ___________________________
products.
