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What are the two different types of culture media?
solid or liquid
What is the purpose of a culture media?
support growth of microorganisms
provide nutrient requirements for specific bacteria
What are culture medias available as?
dehydrated powder to prepare yourself
prepared agar plates
ready-to-use for biochemical tests
What nutrients does an agar typically contain?
What is a peptone?
What do peptones do?
provides amino acids and nitrogen
Are peptones needed for growth of the microorganism?
Are peptones an organic or inorganic salt?
What is the purpose of salt in the agar?
adjusts the osmotic pressure
isotonic for the bacterial cell
What is dextrose and why is it needed in the agar?
source of carbon and energy
Why is water in the agar? What kind of water do we use?
added to provide food material in a soluble form
can be used by the bacteria
used distilled water to ensure uniformity
What is the purpose of meat extract in the agar?
provides water soluble carbohydrates, nitrogen, and vitamins
What are the solidifying agents of an agar?
dried extract of sea algae
not attacked by bacteria
melts at 42 degrees celcius
What are the solidifying agents of gelatin?
animal tissue protein
bacteria attack and liquefy it
melts at 31 degrees celsius
bacteria are usually incubated at 37 degrees celsius
What are the different types of media?
What is an enriched media?
basic nutrient media with added ingredients
What are some of the added ingredients for an enriched media?
What is a selective media?
contains antibacterial substances
inhibits or kills all but a few types of bacteria
facilitates the isolation of a particular genus of bacteria from a mixed colony
What is a differential media?
bacteria can be differentiated into groups
differentiate due to the biochemical reaction on the medium
What is an enrichment media?
favors growth of a particular group of organisms
may contain inhibitory substances that suppress competitors
What is a synthetic media?
prepared from pure chemical substances
exact chemical composition is known
used in experimental work
What is trypticase soy agar?
common basic medium - enriched
What does trypticase soy agar contain?
enzymatic digests of casein and soybean meal
What do we use the trypticase soy agar for?
practicing streak technique
to observe differences in colony morphology
to perform the catalase test