Lab: Enumeration of bacteria

Question 1

4 methods to enumerate bacteria

Answer 1

1. microscopic counts
2. indirect method
3. most probable number
4. standard plate count

Question 2

Microscopic counts

Answer 2

counting cells using microscope

Question 3

indirect method

Answer 3

using a spectrophotometer to read optical density (turbidity)

Question 4

most probable number

Answer 4

typically used with coliforms, tubes with lactose inoculated with water and pattern of tubes showing gas formation compared to statistical tables that give most probable number of coliforms in sample

Question 5

standard plate count

Answer 5

sample diluted in a series then counted

- target is 30-300 cfus