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Microbiology

Terms in this set (27)

What are the three main tests to identify bacteria?
1. Biochemical Test
2. Immunology Test
3. Genetic Test (PCR)
Biochemical Test
look at microbial metabolism
Immunology Test
antibody-based testing
Genetic Test
looks at bacteria's genes
What are the three types of specialized media?
1. Selective Media
2. Enrichment Media
3. Differential Media
Selective Media
some bacteria grow and some don't (selects for a specific bacteria)
Enrichment Media
favors or encourages growth of a particular type of bacteria
Differential Media
distinguish one type of bacteria from another
What type of bacteria does Mannitol Salt Agar select for?
encourages growth of gram positive bactera and inhibits the growth of gram neg bacteria
What component makes Mannitol Salt Agar select for gram + bacteria growth?
the high salt concentration (7.5%)
What component of Mannitol Salt Agar makes the agar a differential agar?
the mannitol (sugar)
What type of specialized agar is Mannitol Salt?
both selective and differential
How do some bacteria convert mannitol into glucose?
fermentation: acid is produced
What does it mean when the color of a Mannitol Salt Agar changes?
High pH = yellow
normally red
What is an example of a bacterium that grows in Mannitol Salt Agars?
Staphalococcus Aureus
What type of specialized agar is Eosin Methylene Blue (EMB)?
selective and differential
What type of bacteria does EMB select for?
gram negative and inhibits growth of gram positive
What component of EMB makes it differential?
Lactose (disaccharide), if able to break bond between glucose and galactose then the bacteria turns metallic green
What is the name of the enzyme that breaks down lactose?
beta-galactosidase
What color does EMB turn if the bacteria can breakdown Lactose?
metallic green
What component causes EMB to be selective?
Eosin Dye
Examples of bacteria that grow in EMB
Escherichia and Citrobacter
-Escherichia Coli
Polysaccharide
20 or more glucose chain
Starch
long chain of glucose
What enzyme does bacteria use to breakdown polysaccharides and starches?
Amylase (exoenzyme)
What does it mean if theres a clear area around a bacteria after preforming a Starch Hydrolysis Test?
The bacteria is able to digest starches
What is starch agar?
a nutrient agar with 5% starch
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