EX 4: Distribution of Microorganisms in the Environment

1. Food of bacteria - carbs, peptones, proteins, vitamins, etc.

2. Indicators

3. Inhibitory substance for certain bacteria - dyes

4. Control pH

What do the components of culture media serve as?

1. According to their Physical State

2. According to their Composition

3. According to their Use

General Classification of Culture Media

1. Solid Media

2. Semi-solid Media

3. Liquid Media

General Classification of Culture Media according to their Physical State

Solid Media

(General Classification of Culture Media according to their Physical State)

Consist mainly of substances mixed with a solidifying agent, gelatin, or albumin matrix. Agar is usually added in concentrations of 2-3%

2-3%

What is the percent concentration of agar in Solid Media?

Semi-Solid Media

(General Classification of Culture Media according to their Physical State)

0.5-1% agar is added to the media

0.5-1%

What is the percent concentration of agar in Semi-Solid Media?

Liquid Media

(General Classification of Culture Media according to their Physical State)

Do not contain solidifying substance

1. Synthetic Media

2. Nonsynthetic Media

3. Living Tissue Media

General Classification of Culture Media according to their Composition

Synthetic Media

(General Classification of Culture Media according to their Composition)

One whose exact chemical composition of the ingredients is known

E.g., Ringer’s solution, Locke’s solution

1. Ringer’s Solution

2. Locke’s Solution

Example of Synthetic Media

Nonsynthetic Media

(General Classification of Culture Media according to their Composition)

The precise composition of some or all of the nutritive elements used not definitely known

E.g., Meat extract broth

Meat Extract Broth

Example of Nonsynthetic Media

Living Tissue Media

(General Classification of Culture Media according to their Composition)

Living cells are present. These are especially used for the cultivation of Rickettsiae and viruses

e.g., HeLa tissue culture medium

RIckettsiae and viruses

What is Living Tissue Media usually used to cultivate?

HeLa Tissue Culture Medium

Example of Living Tissue Media

1. Simple Media

2. Enriched Media

3. Differential Media

   1. Differential Mildly Selective Media

   2. Different Moderately Selective Media

4. Highly Selective Media

5. Transport Media

6. Enrichment Media

General Classification of Culture Media according to their Use

Simple Media

(General Classification of Culture Media according to their Use)

Media which are not enriched and where ordinary organisms are easily cultivated

E.g., Broth or plain agar media

Broth or plain agar media

Example of Simple Media

Enriched Media

(General Classification of Culture Media according to their Use)

These include 5% sheep blood agar, enriched chocolate agar and a number of infusion based media, all of which may be further enriched with additives

1. 5% sheep blood agar

2. Enriched chocolate agar

Example of Enriched Media

Differential Media

(General Classification of Culture Media according to their Use)

These contain dyes, sugars and indicators designed to elicit a characteristic biochemical response (usually a color) are are used to differentiate groups of organisms such as lactose fermenters and non-lactose fermenters

1. Eosin Methylene Blue

2. MacConkey Agar

Differential Mildly Selective Media

1. Salmonella Shigella agar

2. Hektoen Enteric agar

Differential Moderately Selective Media

Highly Selective Media

(General Classification of Culture Media according to their Use)

Promote the growth of a specific organism

1. Löwenstein-Jensen Medium

2. Campy Blood Agar

3. Bismuth Sulfite Agar

Examples of Highly Selective Media

Transport Media

(General Classification of Culture Media according to their Use)

Will prolong the survival of microorganisms when a significant delay occurs between collection and culturing

E.g., Cary Blair TM, Amies TM

1. Cary Blair TM

2. Amies TM

Example of Transport Media

Enrichment Media

(General Classification of Culture Media according to their Use)

Designed for stool cultures where the normal flora of the stool are suppressed favoring the growth of enteropathogens

E.g., Selenite F Broth, Tetrationate Broth

1. Selenite F Broth

2. Tetrationate Broth

Example of Enrichment Media

Enteropathogens

What does Enrichment media favor the growth of?

0.9%

What percent of saline solution is used in Exercise 4?