Quiz 5

Question 1

Urea Hydrolysis Test and results

Answer 1

tests for the presence of urease which can hydrolyze urea into ammonia and CO2
phenol red is red/pink for positive and yellow/orange for negative

Question 2

Tryptone Hydrolysis Test and results

Answer 2

tests for the presence of tryptophanase which can hydrolyze tryptophan into indole and pyruvic acid
Kovac’s reagent creates red ring at the top for positive; no red ring for negative

Question 3

Fat Hydrolysis test and results

Answer 3

tests for lipases which hydrolyze fats into glycerol and fatty acids
Spirit blue agar has a zone of hydrolysis or a dark precipitate (results from lowering pH) for a positive test; no depletion of lipids or ppt for negative

Question 4

Casein hydrolysis test and results

Answer 4

tests for the presence of caseinase which hydrolyzes casein
positive: clear zone of hydrolysis
negative: remains milky white

Question 5

casein is a protein commonly found where?

Answer 5

milk; gives it its white color

Question 6

starch hydrolysis test and results

Answer 6

tests for the presence of amylases that hydrolyze starches
positive: clear zone of hydrolysis after Gram’s iodine added
negative: no clear area, stained brownish-blue by starch-iodine complex

Question 7

IMViC stands for

Answer 7

Indole Production
Methyl Red
Voges-Proskauer
Citrate

Question 8

positive and negative control for spirit blue agar (fat hydrolysis test)

Answer 8

positive: Staphylococcus epidermidis
negative Escherichia coli

Question 9

positive and negative controls for milk agar (casein hydrolysis test)

Answer 9

positive: Bacillus subtilis
negative: Escherichia coli

Question 10

positive and negative controls for starch agar (starch hydrolysis test)

Answer 10

positive: Bacillus subtilis
negative: Escherichia coli

Question 11

which tubes in the API-20E test were anaerobic (mineral oil added)

Answer 11

ADH, LDC, ODC, H2S, URE

Question 12

UVA wavelengths

Answer 12

315-400nm

Question 13

UVB wavelengths

Answer 13

280-315

Question 14

UVC wavelengths

Answer 14

100-280

Question 15

most damaging wavelength to bacteria

Answer 15

265

Question 16

UV light kills bacteria by

Answer 16

causing the formation of pyrimidine dimers (thymine dimers most common) in the DNA

Question 17

which genus survives longer exposure to UV light and why?

Answer 17

Bacillus

Question 18

broad spectrum antibiotics

Answer 18

targets gram positive and gram negative

Question 19

narrow spectrum antibiotics

Answer 19

targets gram positive or gram negative

Question 20

Mueller Hinton Agar requirements

Answer 20

pH 7.2-7.6
thickness of 4.4mm in 100mm Petri dish for correct rate of diffusion
25mL media in 100mm Petri dish

Question 21

effectiveness of an antibiotic measured by:

Answer 21

the zone of inhibition

Question 22

antibiotics vs drugs

Answer 22

antibiotics = microorganisms made
drugs = man-made

Question 23

factors that influence antibiotic diffusion

Answer 23

concentration of antibiotic in disk
molecular weight of antibiotic
solubility of antibiotic in water
pH and ionization
binding to agar

Question 24

reagent added to TDA tube in API-20E test and results

Answer 24

ferric chloride
positive is brown, negative is yellow

Question 25

reagent added to VP tube in API-20E test and results

Answer 25

Barritt’s reagents (a-naphthol and KOH)
positive is pink/red in 10mins

Question 26

reagent added to IND tube in API-20E test and results

Answer 26

Kovac’s reagents
positive is red ring in 2 mins

Question 27

reagent added to the GLU tube in API-20E test and results

Answer 27

sulfanilic acid and N,N dimethyl-l-naphthylamine
positive is red in 2-3mins
confirm negative with addition of zinc