to know in detail about culture media composition used in the field of microbiology
Culture Media
Microorganisms, like other living organisms, require necessary nutrients for the growth and sustenance of life. The food materials on which microbes are grown artificially in a lab is known as culture media.
Media is an environment provided artificially in a lab supplying the required nutrients for the growth of the microorganism.
History
The first person to identify a culture media was Lazaro Spallanzani, and later it was Robert Koch who has developed the same.
Koch first used a cut, half-boiled potato as a base to grow the microbes. Soon, he discovered that the base of the potato, eaten away, then he started using Gelatin.
Gelatin was also not successful as it had a melting point of 21ºC and on incubation gelatin became liquid. Later Mrs Hesse, wife of an associate of Robert Koch, suggested the use of agar which she was suing in her jams and jellies.
The discovery of Agar was a turning point in the history of culture media composition.
Composition of culture media
Different types of culture media composition are identified to isolate, grow and identify them. Different culture media compositions are prepared depending on the nutrient requirement of the microbes.
The essential ingredients of a culture media are as follows
Carbohydrates
Simple and complex sugars are used as a source of carbon and energy.
Examples: Glucose, Lactose, Sucrose
Peptone
Peptone is a source of nitrogen and minerals. It is a water-soluble product obtained from the breakdown of animal or plant protein, and it is a mixture of peptides and amino acids.
Examples: Meat, Soya Bean
Meat Extract
Meat Extract is an aqueous meat infusion made by soaking fresh beef in water and provides the organism with a further supply of vitamins, minerals, sulphates, sulphides essential for the growth of the organism.
Yeast Extract
Yeast Extract is an autolysate made from yeast cells, and it is a common ingredient of culture media due to the presence of the B complex.
Mineral salts
Salts of Sulphur, Magnesium, Phosphorous are used in the media for enzymatic functions.
Agar-Agar
Corneum geladium is a polysaccharide extracted from seaweed, algae belonging to the family Rhodhophyceae, and it contains two main polysaccharides agarose (70-75%) and agar protein (20-25%).
Agar-agar is used as a solidifying agent in the media agent in the media preparation, giving a solid surface for the growth of microorganisms.
Its unique property is that it sets below 40ºC and melts at 90-95ºC. Besides, not attacked by the microbes as it is not a nutrient.
Water
Water is essential as it helps to dissolve all ingredients used for the preparation of the media. Deionized or distilled water is safe to use in the culture media as it is free from the inhibitory effect of chemicals.
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