Media Preparation has become really simple these days. It is quite easy to make any complex media owing to the scientific advancements.
Microorganisms are found everywhere; they are present in soil, water, air, and sewage and on the surface of animal and plant. Hence, they are called as omnivorous. As a microbiologist, if you wish to isolate the microbes from natural environment and grow it in your laboratory then you need to provide them sufficient nutrients in order to support their growth. Scientists have studied their nutritional requirements and designed synthetic media that you can use for cultivation of your desired microbes. The nutritional requirement varies from microbe to microbe and hence various types of media have been designed.
The growth of microbes in laboratory depends upon the supplied nutrients and physical optimum conditions. The growth of microbes means increase in size and number of microbes. The designed media used for growing microbes are called as culture media. The culture media can be solid, semi solid or liquid state. The solid media can be prepared by using solidifying agent or gelling agent called as agar. The agar is extracted from seaweed (marine plants or algae). The agar is carbohydrate made of hetero-polysaccharides of agarose and agaropectin. The agar is also used in making food jelly. The Agar is used as solidifying agent because of its liquefying and solidifying ability. The agar when added in room temperature water as a powder form, it gets partially dissolve but dissolves completely in boiling water i.e. at 100° C. and solidifies when cooled down. The agar serves as best solidifying agent because the microbes do not digest it. In Semi-solid media contains less percentage of agar the solid media. The liquid media is prepared without agar and as called as Broth. The prepared media can be poured into test tubes or petri plates and used for inoculation of desired microbes.
The solid Nutrient media Nutrient Agar contains Beef Extract (0.3%), Peptone (0.5%), NaCl and Agar (1.5%) in water. These ingredients are commercially available. Beef extract provides Macro and Micro biomolecules, minerals and vital nutrients that support the growth of microbes. Peptones acts as source for nitrogen, amino acids and peptides. Sodium Chloride (NaCl) maintains the osmotic equilibrium of media.
- Agar – 15gm/L
- Peptone – 5 gm/L
- Beef extract – 3 gm/L
- Sodium Chloride – 5 gm/L
- pH – 7.4 ± 0.2
- Weigh the above ingredients as per mentioned in the materials.
- The enlist ingredients are dissolved in 800 ml and it be boiled using Bunsen burner and then volume is made up 1 Litre.
- The ingredients are mixed properly by using magnetic stirrer.
- The pH is checked and adjusted to 7.4 ± 0.2 by using acid or alkali.
- The media is then autoclaved at 121° C for 20 min.
The Nutrient media is prepared by using agar, peptone, beef extract and sodium chloride and its pH is adjusted to 7.4 approx.
The prepared media is autoclaved and now the sterile media is ready for inoculation.
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