Discuss about culture media

Definition ; it is an synthesis method to grow the bacteria from infect material like blood sputum

(1) Basal media,
(2) Enriched media,
(3) Selective media,
(4) Indicator media,
(5) Transport media,
(6) Storage media.

1. BASAL MEDIA Basal media are those that may be used for growth of bacteria that do not need enhancement of the media . Examples: Nutrient broth, nutrient agar and peptone water.

2. ENRICHED MEDIA The media are enriched typically by adding blood, serum or egg. Examples: Enriched media are blood agar and Lowenstein-Jensen media.

3. SELECTIVE MEDIA These media favors the growth of a particular bacterium by inhibit the growth of undesired bacteria and allowing growth of wanted bacteria. Examples: Mac Coney agar, Lowenstein-Jensen media Antibiotic may be added to a medium for reserve.

4. INDICATOR MEDIA. An indicator is included in the medium. A particular organism causes change in the indicator, e.g. blood, neutral red,. Examples: Blood agar and Mac Conkey agar are indicator media.

5. TRANSPORT MEDIA. These media are used when specie-men cannot be cultured soon after collection. Examples: Cary-Blair medium, Stuart medium.

6. STORAGE MEDIA. Media used for storing the bacteria for a long period of time. Examples: Egg saline medium, chalk cooked meat broth.

Nutrient Broth .ox heart is milled and mixed with 1 litre water. 10 g peptone and 5 g sodium chloride are additional, pH is adjusted to 7.3.
Uses As a basal media for the preparation of other media.

Nutrient Agar. It is solid at 37°C. 2.5% agar is added in nutrient broth. It is heated at 100°C to melt the agar and then cooled.

Peptone Water Peptone 1% and sodium chloride 0.5%. It is used as base for sugar media and to test indole formation.

Blood Agar Most commonly used medium. 5-10% defibrinated sheep or horse blood is added to melted agar at 45-50°C. Blood acts as an enrichment material and also as an indicator. Certain bacteria when grown in blood agar produce haemolysis around their colonies.
Chocolate Agar Prepared by heating blood agar. It is used for culture of pneumococcal, gonococcus, meningococcal and Homophiles.

Mac conkey Agar. Most commonly used for enterobac¬teriaceae. It contains agar, peptone, sodium chloride, bile salt, lactose and neutral red. It is a selective and indicator medium

Author: Mahesh Kumar Sharma