Water Quality- Quiz 5

Question 1

Enterobacteriaceae (enterics)

Answer 1

• aerobic or facultative anaerobes
• gram neg
• non endospore forming

Question 2

Coliforms

Answer 2

• ferment lactose, produce acid + gas (durham tubes)
• used as indicator of fecal contamination
• looks like e coli, grown in intestine
• some are pathogenic, but Salmonella is not a coliform bc it doesnt ferment lactose

Question 3

most probable number (MPN)

Answer 3

• stat. estimation of presence of coliforms in mixed envir. samples
• based on addition of decreasing quantity of sample (dilution)
• yes/no fermentation tubes
• divided into 3 phases: presumptive, confirmed, completed

Question 4

joseph lister

Answer 4

surgeon. sprayed surgery room w carbolic acid.

Question 5

1. presumptive test

Answer 5

high dilution inoculated in lactose (non selective) or lauryl tryptose (selective)
•pos is yellow and gas production (presumptive positive, do additional tests)

Question 6

2. confirmed test

Answer 6

examination of positive tube w highest dilution
• transfer to lactose brilliant green bile broth (both selective and differential) inhibit gram pos and gram neg. bacteria

Question 7

if not turbid
if turbid but no gas
if turbid with gas

Answer 7

neg
neg
confirmed pos for coliforms

Question 8

3. completed test

Answer 8

positives from brilliant green streaked to emb plate
•for selective recovery of enterobacteriaeae and gram neg bacilli
•coliforms ferment lactose w pink/purple color
•acids produce dark centers
•looking for cloudy

Question 9

MUG test for b glucoronidase

Answer 9

• carbohydrate degrading enzyme

* breaks MUG into glucuronic acid and 4-methylumbelliferone (blue under uv light)

Question 10

Quanti-tray assay: combines both ONPG and MUG test

Answer 10

• coliforms only (yellow)

* e coli (yellow and blue under uv)

Question 11

ColiLert assay: easy way to conduct MPN analysis

Answer 11

mix water sample w onpg and mug
pour into quanti-tray 
results:
•coliforms only (yellow) 
•e coli (yellow and blue under uv)

Question 12

what is EMB plate in completed test?

Answer 12

Eosin and Methylene Blue.

Question 13

what selects against and what does it favor?

Answer 13

Oxbile and brilliant green