Lab Exam 2

With ___, the organism in the phenol broth tube uses up all the sugar in the tube and begins catabolizing proteins to give the tube a fuchsia color.

If the bacteria can't utilize the sugar in the phenol broth tube, it can go through ___ to turn the tube ___.

Phenol red contains ___, peptone, and the indicator ___.

carbohydrates, phenol red

The ___ is meant to capture the gas released during fermentation.

durham tube

IN the phenol red broth, if the tube turns yellow, it should be reported as ___. If the tube turns fuschia, it should be reported as ___.

In denitrification, NO3- (nitrate) is turned into N2 (nitrogen gas). (T/F)

true

Nitrate reduction is a form of aerobic cellular respiration. (T/F)

false

Nitrate needs to be incubated for 24 hours. (T/F)

false

In the nitrate broth, if you add nitrate reagents A and B and the tube turns red, this is a positive result for the nitrate reduction. (T/F)

true

You add reagents immediately after inoculating the nitrate broth. (T/F)

false

Which type of bacteria are responsible for an inconclusive motility result?

obligate aerobes

We use a loop to inoculate the motility agar. (T/F)

false

Which molecule is responsible for the red color in the test for cellular respiration?

Formazan

What are the two purposes of the motility test?

Whether ATP is produced by cellular respiration & ability to move through watery medium

Lophotrichous bacteria are completely covered by flagella. (T/F)

false

Peroxidase turns turns hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2). (T/F)

true

Where do cells sequester chemical reactions involving oxygen?

lysosomes & peroxisomes

Free radicals are ___.

The procedure for the catalase test is to add drops of hydrogen peroxide to a slide smeared with bacteria and look for bubbles. (T/F)

If no bubbles are produced during the catalase test, what are the two explanations?

A positive result of the coagulase test looks ___.

clumpy

The coaglase test will differentiate between Staphylococcus aureus and Staphylococcus epidermidis because Stapylococcus epidiermidis will turn the rabbit plasma clumpy. (T/F)

false

Staphylococcus aureus uses coagulase to ___.

protect it from white blood cells

Staphylococcus aureus reacts with prothrombin in rabbit plasma. (T/F)

true

Coagulase ___.

turns fibrinogen into fibrin

MSA is which type of agar?

differential & selective

You see a yellow MSA plate. What organism is growing on the plate?

Staphylococcus aureus

On MSA, Staphylococcus epidermis would ___.

grow but keep the plate pink

MSA selects for ___.

halophiles

MSA differentiates based on ___.

the ability to ferment mannitol

We must stab the blood agar in the last quadrant. (T/F)

true

An alpha hemolytic bacteria will turn the plate ___.

green

Complete breakdown of red blood cells is associate with ___.

beta hemolysis

Streptococci are organized ___.

by Lancefield grouping

What is a member of Group A Streps?

streptococcus pyogenes

BEA is only a selective media. (T/F)

false

Streptococcus pyogenes is susceptible to bacitracin. (T/F)

true

The indicator for the oxidase test is ___.

phenylenediamine

A negative oxidase result is good for identifying members of the ___.

Ecterbacteriaceae

The oxidase test detects ___.

cytochrome c oxidase

Positive for oxidase results in a red color. (T/F)

false

Why must the results for the oxidase test be read quickly?

it reacts with oxygen in the air to give a false positive

Lactose non-fermenters are often pathogenic. (T/F)

true

Why would you see only the outer edge of colonies turning red on McConkey Agar?

the bacteria have capsules

What is the indicator of McConkey Agar?

neutral red

Streptococcus pyogenes, a Gram + bacteria, will be able to grow on MacConkey Agar. (T/F)

false

Which reagents make MacConkey Agar selective?

bile salts & crystal violet

What are the indicators for the Triple Sugar Iron Agar test?

phenol red & ferrous ammonium sulfate

The Triple Sugar Iron Agar is good for differentiating members of the Enterobacteriaceae family. (T/F)

true

A black tube result for the Triple Sugar Iron Agar would be reported as ___.

A/A + H2S

Which sugar is added at lower concentration than the others in the Triple Sugar Iron Agar?

glucose

In the Triple Sugar Iron Agar test, you are to stab the inoculating needle all the way to the bottom of the tube and then streaking the surface. (T/F)

true

A rapid urease positive result for the urease test indicates which bacteria?

Proteus vulgaris

A hot pink color indicates a positive result for the urease test. (T/F)

true

What are the products of the reaction of urease breaking down urea?

ammonia & carbon dioxide

The indicator for the citrate test is ___.

bromothymol blue

The Methyl Red test detects:

The IMViC tests are used to differentiate coliforms. (T/F)

true

The methyl red (MR) and Voges-Proskauer (VP) test use the same broth, so two tubes of MR-VP must be taken, one for MR and one for VP. (T/F)

true

Indole comes from the breakdown of ___.

tryptophanase