MicrobioLab quiz 2

carbohydrate fermentation uses what sugars?

1) Lactose

2) Dextrose

3) Sucrose

What is the PH indicator do we use to detect Carbohydrate fermentation?

Phenol red

what tube do we use for Carbohydrate fermentation and why?

Durham tube - to see if there was gas production

how do we know if a bacteria ferments carbs?

The tube changes from red to yellow

+A means...

yellow tube / no gas

+AG means...

Yellow tube / gas

- means...

no fermentation / red tube

TSI-A test uses what kind of tube?

An Agar slant with a butt

the percentage of sucrose and lactose in a TSI-A test?

1%

the percentage of dextrose in a TSI-A test?

0.1%

if the agar slant with a butt is all yellow it ferments...

sucrose and/or lactose

if the agar slant with a butt has just a yellow butt it ferments...

dextrose/glucose

if the agar slant with a butt is all red it ferments...

Nothing :(

Catalase formula:

H2O2 --catalase--> H2O + O2

H2O2 is...

Hydrogen Peroxide

catalase + --->

aerobic

Oxidase means (?)

enzyme cytochrome oxidase

to do a catalase test you must...

Drop H2O2 on a colony and see if it bubbles

(catalase test) if it bubbles right away it is...

aerobic

(catalase test) if it hesitates to bubble but does after a few seconds it is...

facultative anaerobe

(catalase test) if it does not bubble it is...

negative

to do an oxidase test you must...

add 2 drops of P-amino onto a colony

(oxidase test) if it turns maroon/black in ≤40 seconds it is...

positive

(oxidase test) if it just doesn't f*cking change in ≤40 seconds it is...

negative

IMViC stands for...

1) Indole

2) Methyl Red

3) Voges-Proskauer

4) Citrate

Indole test equation

tryptophane --[tryptophase]--> indole + pyruvic acid

what media do we use?

SIM's media

Methyl red lets us know if the bacteria ferments...

Glucose/dextrose into acid

media used (Methyl red):

MR/VP broth

Vogues-Proskauer lets us know if there is a presence of...

Alkaline/alcohol substances

media used (Vogues-Proskauer):

MR/VP broth

citrate test

Citric test sees if the bacteria use's citrate as a...

Carbon source

Nitrate reduction test tells us if a bacteria can...

reduce nitrate into nitrite

Indole reagent after bacteria has cultured:

5 drops of Kovac's

Indole + =

red ring (means it has the enzyme)

indole - =

no change/gold ring (no enzyme)

Reagent for Methyl red is...

Methyl red

+ methyl red test =

red color (acids)

- methyl red test =

no change

VP test turns glucose/dextrose into

2, 3 butanediol

VPA reagant a

α-napthol

VPB =

KOH

+ VP test =

red

- VP test =

no change

if an organism uses Citrate as its Carbon source, there is 2 enzymes:

1) Citrate permease

2) citrase

PH indicator in Citrate test =

Brothymol Blue

+ Citrate test =

blue

- Citrate test =

green

Nitrate reduction steps:

1) add 5 drops of sulfamic acid

2) add 5 drops of α-naphthylamine

3) if tube turns red = (+) nitrates

4) if no change:

5) add a pinch of zinc dust

6) if tube turns red = (-) nitrates

7) if no change = (+) NH3

H2S test looks to see if an organism creates the enzyme:

cysteine desulfurase

media for H2S:

SIM

indicator for H2S:

ferrous sulfate (black ppt)

+ H2S test =

black

- H2S test =

no change

Urease PH indicator

phenol red

if the organism creates a basic PH the color will be:

pink

+ urease test =

pink

- urease test =

no change