Selective, Differential and Enriched media

Exoenzymes allow bacteria to ------ large nutrient molecules into smaller molecules that can be transported into the cell

hydrolyze (break down)

Enriched media

media supplemented by blood or other special nutrients (eg blood agar) to allow growth of organisms that cannot grow on general purpose media.

Voges-Proskauer

test the production of acetoin a nonacid by-product of glucose metabolism. Acetoin is detected by adding VP test reagents that react chemically with acetoin to produce a pink red color. Positive: red Negative: colorless

Indole

tryptophanase hydrolyze the amino acid tryptophan in some organisms to produce ------ After adding the Kovac's reagent: Positive: red color on the surface of the broth Negative: colorless

What is the reaction of starch hydrolysis?

when added the iodine: Blue-black color is negative Color of iodine is positive

IMViC test

Consist of four test I: Indole M: Methyl red test V: Voges-Proskauer C: Citrate

Enzymes which are secreted to the outside of the cell are termed....

Exoenzymes

Bacteria that are unable to lyse red blood cells will make no apparent change in blood agar around the colonies are term....

Gamma hemolysis

What is the term for the media that support the growth of a variety of microbes? Give an example of those we used in our lab.

General purpose media. Nutrient Agar and Tryptic Soy Agar.

Eosin Methylene Blue (EMB) is selective for

Gram Negative, but inhibit the growth of Gram Positive

Phenylethyl alcohol Agar (PEA) is selective for

Gram Positive but inhibit the growth of Gram Negative

Mannitol Salt Agar (MSA)

Is both selective and differential. ----- contains 7.5% NaCl and selects for salt tolerant bacteria.

What is the Ph indicator of MSA?

Phenol red

What is the term for the media that contains dyes or toxics substances which inhibit the growth of certain microbes, but support the growth of others?

Selective Media

What is the selective agent for Mannitol salt Agar (MSA)?

Sodium Chloride

Enzymes are very specific for their ------

Substrate (the substance the enzyme acts on)

Starch Hydrolysis/ Amylase

------ is a polysaccharide which some bacteria can digest by producing the enzyme------

Catalase Production

-Media: nutrient agar -Enzyme: catalase -Reagent: Hydrogen peroxide -Result: produces bubbles, positive for catalase

Bacteria that partially lyse red blood cells and form a greenish-brown zone around the colonies are called....

Alpha hemolytic

Bacteria that completely lyse red blood cells will form a clear zone around the colonies are term...

Beta hemolytic

Gelatin hydrolysis

Can be hydrolyzed by bacteria producing the enzyme gelatinase Positive: liquifies Negative: Solidify

Casein hydrolysis

Used to identify organisms able to hydrolyze casein. Positive: clear zone Negative: No change

Methyl red test ( mixed acid fermentation)

Uses a medium that contains glucose- MRVP- produce strong acids Ph indicator: Methyl red Positive: red at PH 4.4 Yellow at Ph 6.2

Blood Agar (BA)

________ is both enriched and differential. ________ is differential based on hemolytic patterns.

Differential media

a media which differentiates or distinguishes between different types of microorganisms based on differences in appearance of growth or color changes. EMB is selective and differential because bacteria that ferment lactose produce dark purple colonies or a metallic green sheen on the media.

Citrate - Simmons citrate agar

contains sodium citrate as the sole carbon source. Produce ammonia Ph indicator: Bromthycol blue Positive: Blue Negative: Green