Axenic Culture:
Definition: Axenic culture is the state of a culture in which only a single species variety or strain of organism is present and entirely free of all other contaminating organisms.
- Microorganisms can be grown under controlled laboratory conditions in cultures where they are allowed to grow and reproduce.
- Microorganisms are grown largely for research, taxonomic, and medical purposes.
- An axenic culture though could be a culture containing only one species, variety or strain of organisms. organisms that are obligate symbiotic though cannot be grown in axenic cultures.
- Axenic cultures can be prepared by picking out a single cell that would initiate a culture.
- This technique is useful in growing a specific culture of fungi, algae, and certain bacteria.
- In bacteria series of streak plate technique can be used in order to separate microbial population and achieve an isolated colony of cells uncontaminated with other microbes.
- Other way to achieve axenic culture is the addition of antibiotics to prevent the growth of certain cells.
Sub Culturing
Subculture refers to the transfer of cells from one culture vessel to another culture vessel.
There are two types of subcultures
1. Mono layer subculture and
2. Suspension subculture
1. Mono layer subculture
When the bottom of the culture vessel is covered with a continuous layer of cells, usually one cell in thickness, they are referred to as mono layer culture.
Technique of Mono layer subculture
It consists of fallowing steps
- Removal of the medium
- Brief exposure of the cells to trypsin
- Removal of trypsin and dispersion in a medium
- Incubation of cells to round up
- Re-suspension of the cells in a medium for counting and reseeding
- Cells reseeded and growth to mono layer.
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| Mono layer subculture |
2. Suspension subculture
Majority of continuous cells lines grow as mono layer. Some of the cells which are non-adhesive e.g. cells of leukemia can be propagated in suspension.
Techniques of suspension culture
The cells can be suspended in a culture flask(stirrer flask) containing the desired medium. The medium is continuously stirred with a magnetic pendulum rotating at the base of the flask. The cells have to periodically examined for contamination or signs of deterioration.
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| Suspension subculture |
