Quiz 5

Coliforms are used as an indicator organisms of fecal contamination of water because

a. They are usually non-pathogenic, although they can be opportunistic pathogens.

b. They ferment lactose.

c. They are abundant in human and animal feces.

d. All of the above.

All of above

Helicobacter pylori a pathogen in the human stomach produces a large amount of __ to neutralize the acidic pH of the stomach
a. Protease

• b. Lactase

• c. Amylase

• d. Urease

urease

Indole test with MIO agar is performed to detect __
a. Ornithine decarboxylase activity

b. Phenylalanine catabolism

c. Tryptophan catabolism

d. H₂S production

tryptophan catabolism

If an organims uses glucose aerobically but NOT anaerobically the results in OF glucose medium are
a. Yellow in both tubes (with and without oil)

• b. Yellow with oil, green without oil

• c. Green with oil, yellow without oil

• d. Green in both tubes

green color in tube with oil overlay and yellow color in the tube with out oil overlay

enterobacter aerogenes produes __ if it shoes a postive result from the VP

acetoin

During anaerobic respiration some bacteri reduce nitrate to __ which other bacteria further reduce to nitrous acid and nitrogen gas

nitrite

if a bacterium uses citrate as a C-source. what change in the ph will occur and why ?

acid become basic bc ammonia is being produced

plaques can be formed only by “infections” phage why ?

bc lytic phages kill bacteria and produce clear plaques

What bacterium do you want to detect at the end of the water microbiology analysis?

e.coli

could the water have a high # of the pathogenic becterium vibrio cholerae and give negative results ,

yes virbrio isnt a lactose fermenting coliform so the coliform test can be negative even if its present