MicroLabQuiz3

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Phenol red sugar fermentation purpose?

Fermentation of various sugars by bacteria

Phenol red sugar fermentation Media/substrate

Media: Phenol red broth

substrate: Glucose, lactose, maltose or mannitol

Phenol red sugar fermentation Reagent

None added, phenol red is the pH indicator that changes color

Phenol red sugar fermentation Product

Acid or Acid & Gas

Phenol red sugar fermentation Positive appearance?

Yellow/ bubble will be present if positive for gas

Phenol red sugar fermentation Positive control organism?

E. coli

Methyl red purpose/Enzyme?

Fermentation of glucose

Methyl red media/ substrate

Media: MR-VP broth

substrate: Glucose

Methyl red Reagent

Answer: methyl red

Methyl red Product

Mixed acids

Methyl red Positive appearance?

Red layer

Methyl red Positive control organism

E. coli

Voges-Proskauer (VP) purpose/enzyme?

Fermentation of glucose

Voges-Proskauer (VP) media/ substrate

Media: MR-VP

broth

Substrate: Glucose

Voges-Proskauer (VP) Reagent

VP a & VP b

Voges-Proskauer (VP) Product

Acetoin

2,3- butanediole

Voges-Proskauer (VP) Positive appearance?

Pinkish color after 5 mins of agitating

Voges-Proskauer (VP) positive control organism?

E. Aerogenes

catalase purpose/ enzyme?

Test for presence of catalase enzyme

Catalase media/ substrate

Media: TSA slant

substrate: hydrogen peroxide

Catalase reagent

Hydrogen peroxide

Catalase product?

Oxygen & water

Catalase positive appearance?

Bubbles

Catalase postive organism?

Staphylococcus

oxidase Purpose/ enzyme?

Test for the presence of cytochrome C oxidase

Oxidase media/ substrate

No media used - bacteria placed on filter paper and reagent added

Oxidase reagent

Oxidase

Oxidase product?

None

Oxidase positive appearance?

Blue color change in 10 seconds

Oxidase positive control organism

Pseudomonas

nitrate reduction purpose/ enzyme?

Test for the presence of nitrate reductase

Nitrate reduction media/ substrate

Media: NSI broth with Durham tube

nitrate reduction reagent

Red reagent A and B

nitrate reduction Product?

Nitrite

nitrate reduction positive appearance?

Media darkens red

nitrate reduction positive control organism

Enterobacteriaceae

starch hydrolysis Purpose/ enzyme?

Test for the presences of Amylase

starch hydrolysis Media/ substrate

Media:Starch agar plate

Substrate: Starch

starch hydrolysis Reagent

Iodine

starch hydrolysis Product?

Glucose

starch hydrolysis positive appearance?

Clear area (halo) around bacterial

growth

Starch hydrolysis positive control organism

Bacillus

citrate utilization Purpose/ enzyme?

Citrate is used as the sole source of carbon (enzyme citrase)

citrate utilization Media/ substrate

Media:Simmons Citrate slant

Substrate: citrate

(picture is a example of Simmons citrate slant)

citrate utilization reagent

None added, bromothymol blue is the pH indicator

citrate utilization product?

Ammonium Hydroxide

citrate utilization Positive appearance?

Royla Blue

citrate utilization positive control organism?

E. aerogenes

tryptophan hydrolysis purpose/ enzyme?

Test for the presence of

Tryptoophanase

tryptophan hydrolysis Media/ substrate

SIM media substrate: tryptophan

tryptophan hydrolysis reagent

Kovac's reagent (indole)

tryptophan hydrolysis Product?

Indole

tryptophan hydrolysis positive appearance?

Red layer

tryptophan hydrolysis positive control organism?

E. Coli

H2S production purpose/ enzyme?

Test for the ability of bacteria to reduce sulfer to Hydrogen Sulfide

H2S production media/ substrate

SIM media Substrate: Sulfur

H2S production reagent

None added

H2S production product?

Sulfide Production, FeS (ferric sulfide)

H2S production positive appearance?

Black precipitate

H2S production positive control organism?

Proteus

urea hydrolysis Product/ enzyme?

Test for the presence of Urease

urea hydrolysis Media/ substrate

Media: Urea broth

Substrate: Urea

urea hydrolysis reagent

None added, but phenol red is the pH indicator

Urea hydrolysis product?

Ammonia and carbon dioxide

urea hydrolysis Positive appearance?

Shocking pink

urea hydrolysis Positive control organism?

Proteus