Lab Quiz 3

What labs used differential media?

BA, Choc, SIM, TSI, PR, NIT, MRVP, DNase, Starch, Citrate, Lys

Nutrient utilization for differential media

carbon and nitrogen

Amino acid metabolism for differential media

decarboxylation and deamination

Energy metabolism for differential media

fermentation and respiration (aerobic/anaerobic)

Deamination

results in the production of an organic acid and ammonia; increases pH

Decarboxylation

results in the production of basic amines; increases pH

Substrate of Blood Agar

sheep's blood

Indicator of Blood Agar

red blood cells

Alpha type of hemolysis

partial destruction of red blood cells; produces greenish color around the growth

Beta type of hemolysis

complete destruction of red blood cells; clearing around growth in the media

Gamma type of hemolysis

no hemolysis; appears as growth without a change in the media

Chocolate Agar

an enriched medium used to grow fastidious organisms and aerobic bacteria ; can be made selective

Composition of TSI

substrates: glucose, sucrose, fructose (fermentable), sodium thiosulfate; 2 indicators: phenol red, ferric ammonium citrate

TSI tests for what metabolic properties?

sugar fermentation, sulfur reduction (only occur in acidic env & anaerobic), gas production

Match the following TSI lab results: yellow butt/ yellow slant and cracking of the agar

glucose + lactose and/or sucrose and gas production

Match the following TSI lab results: yellow butt/ red slant

glucose only fermenter, strictly aerobic, increase in pH, gas production may or may not occur

Match the following TSI lab results: some red slant but mostly black

reduction of sodium thiosulfate led to formation of h2s

Match the following TSI lab results: red/pink slant, no change in butt

non-fermenter, amino acid degrader, obligate aerobe

Match the following TSI lab results: red/pink slant, red/pink butt

organism can degrade peptone aerobically and anaerobically

Hydrolytic reactions of differential media

presence or absence of enzymes; can be extracellular or intracellular

All forms of fermentation are ?

substrate level of phosphorylation

Thayer-Martin medium

chocolate agar with antibiotic, selective for Neisseria gonorrhoeae

Bacitracin

chocolate agar with antibiotic, selective for Hemophilus influenza

Substrate of chocolate agar

lysed red blood cells

True or False: A slant with a deep butt creates both aerobic and anaerobic environments

True

With TSI we may also see what type of degradation?

Peptone (protein breakdown)

What is the name of the process where the slant turns red due to increase in pH?

reversion

What does it mean if after inoculation you see a change of color to black? This happens in any media

sulfur was reduced which leads to the formation of hydrogen sulfide and creates a black precipitate

SIM tests for what metabolic properties?

sulfur reduction, indole production and motility

Substrates for SIM

sodium thiosulfate, tryptophan and agar

Indicators for SIM

ferrous ammonium sulfate, Kovac's reagent, turbidity

Match the following SIM lab results: clear tube, not turbid, yellow color after Kovac addition

negative for sulfur reduction, indole production and motility

Match the following SIM lab results: clear tube, turbid, red color (ring on top) after Kovac addition

negative for sulfur reduction and positive for both motility and indole production

Match the following SIM lab results: black tube, turbid, yellow (no red ring) color after Kovac addition

positive for sulfur reduction and motility; negative indole production

Match the following SIM lab results: only clear growth around stab mark, no pink ring

sulfur reduction(-), motility(-) and indole production(-)

Phenol red tests for what metabolic properties?

Lactose fermentation, deamination (degrade peptone), and gas production

Substrate of phenol red broth

Lactose

Indicator of phenol red broth

phenol red (for acid) and durham tube (indicator of gas)

Match the following Phenol Red lab results: red color of broth and no bubbles

lactose fermentation (-), deamination (-), gas production (-)

Match the following Phenol Red lab results: yellow coloration of broth and with air bubbles

lactose fermentation (+), deamination (-), gas production (+)

Match the following Phenol Red lab results: pink color of broth and no bubbles

lactose fermentation (-), deamination (+), gas production (-)

MR-VP tests for what metabolic properties?

MR tests determines if the org fermented glucose via the mixed acid fermentation pathway; VP tests determines if the org fermented glucose via the 3,2-butanediol pathway

1 multiple choice option

Substrate of MR-VP

glucose for both

Indicator of MR

methyl red dye

Indicator of VP

alpha-naphthol (reagent A) and KOH (reagent B)

Match the following MR lab results: red coloration

only true positive result, acidic

Match the following MR lab results: red or copper coloration

negative to mixed acid fermentation pathway

Match the following VP lab results: red coloration

positive to 3,2-Butanediol pathway, alkaline

Nitrate broth tests for what metabolic properties?

nitrate reduction to either nitrate, molecular nitrogen (denitrification) or some other nitrogenous compound

substrate of nitrate reduction test

potassium nitrate (KNO3)

Indicators of nitrate reduction test

sulfanilic acid (reagent A), alpha-naphthylamine (reagent B), zinc powder, durham tube

Match the following Nitrate lab results: Red coloration after A & B

positive for nitrite (nitrate reduced to nitrite)

Match the following Nitrate lab results: No color after A & B, red after Zinc

negative (nitrate not reduced)

Match the following Nitrate lab results: no color after zinc

positive for nitrite

Match the following Nitrate lab results: bubble in Durham tube

denitrification

DNase tests for what?

presence of enzyme DNase

What are the most frequently used amino acids in a decarboxylation test?

ornithine, lysine and arginine

What is the substrate of a DNase test?

DNA

What is the indicator of a DNase test?

methyl green dye

Match the following DNase test results: loss of green blue color/clearing around growth

DNase present

Match the following DNase test results: no loss of color/clearing around growth

DNase absent

1 multiple choice option

Decarboxylation will raise or lower the pH?

raise the pH

1 multiple choice option

Lysine decarboxylation tests for what?

fermentation of glucose and presence of the enzyme lysine decarboxylation

What is the substrate of a Lysine decarboxylation test?

peptone (lysine) and glucose (for acid trigger)

What is the indicator of a Lysine decarboxylation test?

bromocresol purple

Match the following lysine decarboxylation test results: no color change

no glucose fermentation and no lysine decarboxylation

Match the following lysine decarboxylation test results: only yellow coloration

fermentation of glucose but no lysine decarboxylation

Match the following lysine decarboxylation test results: yellow and purple coloration

fermentation of glucose and lysine decarboxylation

Mineral oil

for lysine decarboxylation test, it must be added after inoculation to seal out oxygen and promote fermentation

In a lysine decarboxylation test, glucose fermentation initially turns the media what color?

yellow (low pH)

Lysine decarboxylation reverts the media back to what color?

purple (high pH)

Citrate Agar tests for what?

presence of citrate permease enzyme and the ability to use citrate as the sole carbon source

Substrate of citrate agar

sodium citrate and ammonium dihydrogen phosphate

Indicator of citrate agar

bromothymol blue

Citrate permease

brings citrate inside the cell; orgs w/out this enzyme will not grow on citrate media

Citrate lyase

converts citrate to oxaloacetate and acetate, generates energy for the cell

Match the following Citrate Agar test results: growth with color change to blue

citrate positive

Match the following Citrate Agar test results: growth with no color change to blue

citrate positive

Match the following Citrate Agar test results: no growth

citrate negative

What does a Starch Hydrolysis test for?

for linear polysaccharide, the presence of enzyme amylase and for branch points in polysaccharide oligo-1,6-glucosidase

Substrate in a Starch Hydrolysis Test

starch

Indicator in a starch hydrolysis test

iodine (added after incubation)

Match the following Starch Hydrolysis test results: clearing around growth with iodine indicator and no brown discoloration around growth

α-amylase, β-amylase, and/or α-1,6-glucosidase is/are present (positive)

Match the following Starch Hydrolysis test results: no clearing around growth with iodine indicator or brown discoloration around growth

α-amylase, β-amylase, and/or α-1,6-glucosidase is/are not present (negative)

What does a Catalase test for?

presence of enzyme catalase which breaks down hydrogen peroxide to water and oxygen gas

Substrate in a Catalase test

hydrogen peroxide

Indicator in a Catalase test

bubble formation

Match the following Catalase test results: formation of bubbles

catalase (+)

Match the following Catalase test results: no bubbles

catalase (-)

What does Oxidase test for?

presence of cytochrome c oxidase

Substrate in oxidase test

TMPD

Indicator in oxidase test

color change

Match the following Oxidase test results: color change to blue

oxidase (+)

Match the following Oxidase test results: no color change or change to cream

oxidase (-)

What does Coagulase test for?

presence of coagulase enzyme and used to identify staphylococcus aureus

substrate in coagulase test

plasma

Indicator in coagulase test

clot formation

Match the following Coagulase test results: no clumping

coagulase (-)

Match the following Coagulase test results: clumping

coagulase (+)