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Index >> Growth of Microorganism >> Synchronous Cultures of Microorganisms

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Growth of Microorganism Part 1 Physiological Functions of Trace Elements Vitamins and Their Functions Methods of Determining Growth Ectosymbioses Endosymbioses Functions of Symbiosis Rhizosphere and Phyllosphere Mycorrhizae Root Nodule Bacteria and Legumes Root Nodule Bateria and nonlegumes Lichens

Synchronous Cultures of Microorganisms

	Synchronous Cultures of Microorganisms - The cell cycle of unicellular yeast or bacterium includes all the stages from a single cell upto the formation of two cells. It is however, not necessary that the demarcating point be only the division but can be even the septum formation or any other clearly observable characteristic. If septum formation is taken as the starting point, the division cycle represents all events that occur between one septum formation to the other. An exponentially growing culture contains cells which are distributed among various stages of growth and the division cycle.
Analysis of such populations will therefore yield only average values for any parameter. To understand the properties of an individual cell during the course of its division cycle, it is necessary that we analyse each cell individually. This has practical limitations since it is not possible to examine the behaviour of a single cell easily.
A system that closely resembles and amplifies the behaviour of single cells is synchronous culture which contains cells that are physiologically identical and are in the same stage of division cycle. A synchronous population can be generated either by physically separating cells in the same stage of division or by forcing a cell population to attain an identical, physiological condition by a change in the environment Several methods are today available for obtaining such synchronously dividing cell populations. These include physical separation of the Cells by centrifugation, filtration or by periodic changes in nutritional and environmental conditions.
In a synchronous culture since the cells are physiologically identical cell division occurs periodically at constant intervals other cell properties such as dry mass, optical density, total protein or RNA content per cell increase at a constant rate but the amount per ml of culture will increase in, proportion to the cell number.
	On the other hand, the pattern of DNA synthesis can be either periodic or continuous depending on how fast the culture is growing. For example, E. cob growing In a medium with a generation time of less than 40 minutes will show continuous DNA synthesis, while growing with generation times greater than 40 minutes, will show a period when no DNA synthesis occurs. Although such synchronous cultures serve as excellent amplifications of a Single cell system, their useful ness is restricted since perfect synchrony can be had only for 2 to 3 division cycles. In recent years, a further improvement has been made to obtain information regarding individual cell cycles. In this, a culture of cells growing exponentially is centrifuged either in sucrose, glycerol or sorbitol gradients to separate cells based on their densities which is directly related to their age.

Analysis of such fractions from gradient centrifugation has provided the same information as one would get from using synchronous cultures .

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Growth of Microorganisms Part 1 Cyanellae Zoochlorella and Zooxanthellae Endosymbiosis of Algae Normal Flora of Human Ruminant Symbiosis Ectosymbioses of Microbes Ectosymbioses of Protozoa Endosymbioses of Fungi Continous Cultures Synchronous Cultures Diauxic Growth Factors Affecting Growth and Growth Rates

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