Midterm: Media

Question 1

What is the overall purpose of media in the microbiology lab?

Answer 1

To grow and maintain growth of bacteria and microbes for extended periods of time

Question 2

What are the three categories of media classification?

Answer 2

General purpose

Selective media

Differential media

Question 3

What is the difference between a “defined media” and a “complex media”?

Answer 3

Defined media has every molecule accounted for. Complex media contains ingredients whose exact chemical content is not defined.

Question 4

Why might a microbiologist use a general purpose media when taking environment samples, with no particular species or type of microbe in mind?

Answer 4

General purpose media is used to grow a wide variety of microbes.

Question 5

What type of microbe is an enriched media designed to grow?

Answer 5

Fastidious microbes

Question 6

What is the purpose of selective media?

Answer 6

Contains one or more agents that make it inhibitory for certain microbes to grow.

Question 7

What is the purpose of a differential media?

Answer 7

Allows multiple types of microorganisms to grow but creates differentiation between the microbes

Question 8

Approximately what percent of microbes are culturable in the lab?

Answer 8

Less than 1%

Question 9

What factors limit the growth of microbes in the lab?

Answer 9

1) Lack of nutrients
2) pH requirements not met
3) oxygen levels too high/low
4) need other microbes around them to grow
5) may require 3D growth chamber

Question 10

How do scientists know microbes can’t be grown in the lab?

Answer 10

Direct count vs. culture count- directly counting under a microscope then attempting to culture

Genetic analysis- analyze DNA directly from the environment