Presumptive Test- Lab 41

Question 1

List the three steps of water testing in order

Answer 1

1. Presumptive test
2. Confirmed test
3. Completed test

Question 2

What constitutes a positive presumptive test

Answer 2

Production of acid is determined by the change of the medium from green to yellow.
Production of gas you look for a gas bubble in the durham tube

Question 3

What do yellow and blue tubes with no bubbles indicate

Answer 3

Negative

Question 4

Define coliforms

Answer 4

All facultative anaerobic gram-negative rods which produce acid & gas from lactose fermentation in 48 hours and 35°C