counting/measuring microorganisms

Question 1

What are two direct methods of counting/measuring microorgansims?

Answer 1

plate count and membrane filteration

Question 2

what is a plate count?

Answer 2

add measured amount of the sample to growth media, then count colonies that form

Question 3

what is membrane filteration?

Answer 3

filter organisms onto membrane with a grid. you would count the organisms in a few grids and multiply by number of grids

Question 4

what is a downside to using membrane filteration?

Answer 4

it counts the dead organsisms too

Question 5

What are two indirect methods?

Answer 5

Turbidity and Luceferin

Question 6

what is turbidity?

Answer 6

used in clear fluids, measures the cloudiness of sampl, but only works in high concentrations

Question 7

what is luceferin?

Answer 7

it detects the presence of ATP produced by bacteria in foods or on surfaces

Question 8

what is luceferin used for?

Answer 8

moniter sterility in food processing centers, operating rooms, etc.