Basic Techniques of Microbiology

These techniques mainly involve methods for culturing microbes. There are several culture techniques. Let’s have a brief discussion on some of the common culture techniques.

1. Enrichment culture technique
   

   It involves use of enrichment media that will help in growth of particular bacteria against the other that are present in the given sample because of its specialized nutrient utilization capability and other such metabolic properties. Microbes who can tolerate the constituents of the selective media can only grow in that selective media.

2. Spread plate and pour plate culture techniques
   

   Spread plate method is used for culture of special clonal colonies and pour plate method is used for counting the specific number of colonies in a liquid medium.

3. Streak plate technique
   

   This is a technique of getting the isolated colonies from a discreate colony by transferring it to the agar slant or plate of same composition. An inoculating loop is used for transferring the microorganism.

Maintenance and Storage of Microbes Techniques

The sole purpose of maintenance is keeping microorganism alive that too in such a way that there is no change in their phenotypes in relation to their original isolates. It is highly essential to keep the microbial cells free from contamination, keep them viable and also keep their genetic material unaltered as much as possible. The various techniques involved in maintenance and storage are

1. Sub cultivation
   

   Sub-cultivation is done by transferring some or all cells to a fresh growth medium to keep them viable for a long period of time. Thus, it is one type of storage techniques for microbes.

2. Lyophilization
   

   It is one of the important methods used for long term preservation of microbes. It is a multi-step process that mainly involves microbe culture, then suspension of this culture in a lyophilization medium and then putting them to freezing process and then storing them in proper manner.

3. Liquid nitrogen storage
   

   This involves storage of microbes in a temperature between -196^oC and -150^oC in liquid nitrogen for a long period of time.

Identification of Microbes’ Techniques

This mainly involves techniques or methodologies used for identification of microbes.

1. Staining

   Staining is a method of identifying microbes by study of their cell properties. It is an axillary technique utilized in microscopy for increasing the contrast in a microscopic image. It mainly involves five types.

   • Simple staining-It involves application of a single dye to the microbial smear. Basic dyes used are crystal violet, methylene blue etc.
   • Differential staining: It is utilized for distinguishing organisms depending on their staining properties. Here the smears are exposed to more than one dye.
   • Gram staining: It is one of the most important and widely used staining techniques that differentiates the bacteria into two major groups that is gram negative and gram positive. Smear is stained with a basic crystal violet and then with iodine solution which act as mordant. The difference in the response to the stain helps in knowing about the physical and chemical properties of the cell walls.
   • Acid fast staining: It is another important differential staining process used for identification of mycobacterium sp.
   • Endospore staining: It is used for identification of endospores. The dye used in this technique is malachite green.

   Then apart from all this some other staining techniques are there for identification of fungus like lactophenol cotton blue staining, and many other techniques.

2. Biochemical tests

   The sole purpose of biochemical test in microbiology is to differentiate between various classes of bacteria by studying their enzymatic activities. Various biochemical tests are Indole test, methyl red- vogues praousker test, catalase, oxidase, etc.

3. Motility test

   It is another important technique where the motility capability of an organism is access to differentiate between various organisms.

4. Antimicrobial sensitivity techniques

   It is one of the most prevalent techniques used in determining to which particular antibiotic the microbe is sensitive to. Knowing this can help in preventing diseases caused by that particular microorganism. This is the reason why this process has so much importance in the field of microbiology. Various antimicrobial susceptibility test is Dilution method, disk-diffusion method, Genotypic method, etc.

Apart from all these there are vast numbers of other techniques used in microbiology that is important not only for microbiological study but also for other sectors.