Continous Cultures,Culture Systems,Cell Biomass,Turbidostat Cells,Chemostats Types,Cell Growth,Metabolism

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	Continous Cultures - In a continuous culture, the cell population is maintained in a steady state by regularly replacing a portion of the used or spent medium by fresh medium. Such culture systems are of either (1) closed or (2) open type. In a closed continuous culture, cells are separated from the used medium taken out for replacement, and added back to the culture so that cell biomass keeps on increasing. In contrast, both cells and the used medium are taken out from open continuous cultures and replaced by equal volume of fresh medium.
The replacement volume is so adjusted that cultures remain at submaximal growth indefinitely. The open cultures are of either turbidostat or chemostat types. In a turbidostat, cells are allowed to grow up to a preselected turbidity (usually measured as OD) when a predetermined volume of the culture is replaced by fresh normal culture medium. But in a chemostat, a chosen nutrient is kept in a concentration so that it is depleted very rapidly to become growth limiting, while other nutrients are still in concentrations higher than required. In such a situation, any addition of the growth limiting nutrient is reflected in cell growth. Chemostats are ideal for the determination of effects of individual nutrients on cell growth and metabolism.