Water Lab

Question 1

What temperature and time do you incubate R2A media at?

Answer 1

20-28C for 5-7 days. (or 35C for 3-7 days)

Question 2

WHat is the sample size of recreational water?

Answer 2

100mL

Question 3

What is the purpose of using brilliant green bile salts in water testing?

Answer 3

Bile salts inhibit non-coliform bacteria selecting for total coliforms.

Question 4

What is the purpose of R2A media?

Answer 4

A low nutrient agar used to recover stressed chlorine-tolerant organism from drinking water.

Question 5

What is the minimum volume of environmental water collected to do MPN testing?

Answer 5

100mL

Question 6

What do MUG and ONPG tests of detect?

Answer 6

MUG detects E. coli (fluorescence) and ONPG detects total coliforms (yellow).

Question 7

How do you transport a water specimen?

Answer 7

In a cooler on ice to keep it cold.

Question 8

EPA shake.

Answer 8

Shake the bottle 25 times for 7 seconds in a 1 foot arc.

Question 9

Define MPN.

Answer 9

Most Probable Number. It is an estimation of the most likely number or organisms present based on statistical evaluation of tests from which there are only two outcomes (organism present or not present). It is not an actual enumeration.