The cultivation method of bacteria is a technique of multiplying microorganisms in predetermined culture media. Microbial cultures can evaluate the type of organism.
Purpose of culturing
- Isolation of bacteria
- Studying bacterial morphology and its identification
- Maintenance of stock cultures
- Estimate viable counts
- To check for antibiotic sensitivity
- To make antigens for laboratory use
What is a Pure culture?
In the laboratory, bacteria are isolated and grown in pure culture in order to review the functions of a specific species, and then we observe pure culture that is a population of cells growing within the absence of other species or types.
Pure cultures are obtained by using some sort of special techniques. Aseptic techniques are used to obtain pure cultures therefore, it’s important that all glassware, media, and instruments must be sterilized. Therefore, basic requirements for obtaining a pure culture are a solid medium, and a media container that can be maintained in an aseptic condition, and a way to separate individual cells. One bacterium, provided with the right nutrients, and will multiply on the solid medium during a limited area to form a colony, which may be a mass of cells all descended from the initial one.
What are different cultivation methods of bacteria?
Culture methods are one of the most important laboratory-growth methods in which bacterial growth is studied and they are basic diagnostic methods that serve extensively as a research tool in molecular biology. Hence different methods of culture are as follows:
1. Streak culture
It is used for the isolation of bacteria in pure culture from clinical specimens in which platinum wire is employed and one loop is filled with the specimen is transferred onto the surface of a well dried plate adjoining a little area at the periphery. But the inoculum is then distributed thinly over the plate by streaking it with a loop during a series of parallel lines in several segments of the plate. Separated colonies are thus formed over the last series of streaks on incubation.
2. Lawn Culture
It provides a consistent surface growth of the bacterium. It is prepared by flooding the surface of the plate with a liquid suspension of the bacterium. Therefore, lawn culture is used for bacteriophage typing, and antibiotic sensitivity testing, and for the preparation of bacterial antigens and vaccines.
3. Stroke Culture
It acquires a pure growth of the bacteria for slide agglutination and a few other diagnostic purposes.
4. Stab Culture
This culture is however prepared by puncturing an appropriate medium – gelatin or glucose agar with an extended, and straight, and charging wire. However the major uses include the demonstration of gelatin liquefaction, oxygen requirements of the bacterium under study, and the maintenance of stock cultures.
5. Pour Plate Culture
1 ml of the vaccine is poured into the molten agar. This is mixed well and added to a sterile Petri dish and then allow to line depth of the medium. And then the pour plate culture is used for the bacterial count, and estimation of the viable suspension, and for the quantitative urine cultures.
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