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Index >> Growth of Microorganism >> Microorganisms Nutritional Classification

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Growth of Microorganism Growth of Microorganisms Part 2 Lag phase Exponential phase Deceleration Phase Acceleration Phase Stationary Phase Death Phase Mycelial Growth Synchronous Growth Fed Batch Culture Continous Culture Distribution of Microorganisms Environmental Factors affecting Microbial Growth Biogeochemical Cycling of Elements

Microorganisms Nutritional Classification

	Microorganisms Nutritional Classification -Although organisms can be grouped based on their relationship to molecular oxygen, they can also be grouped in relation to their nutritional requirements. Broadly two groups are recognized. (i) Autotrophs - which can utilize, inorganic nutrients or light as a source of energy, e.g. nitrifying bacteria, algae, etc., and (ii) Heterotrophs - which require organic compounds as a source of energy, e.g. many bacteria, fungi and protozoa. Although this classification is relatively simple it does not allow us to distinguish organisms based on their energy requirement and the principal carbon source.
Currently microorganisms are grouped into four major groups based on the above parameters. 1. Photoautotrophs - which use light as an energy source and CO2 as the carbon source e.g. algae and many photosynthetic bacteria 2. Photoheterotrophs- which use light as the energy source and reduced organic compounds as a carbon source. Example purple non sulphur Bacteria.
3. Chemoautorophs - which use inorganic chemicals as an source and CO2 as a principal carbon source. These organisms Obtain their energy by the oxidation of reduced inorganic compounds such as NH3, NO'2, H2, H2S and Fe++. These organisms are also called chemolithothrophs since these can grow in an inorganic medium in the absence of light. 4. Chemoheterotrophs - which use organic compounds as an source as well as a principal carbon source. The clear distinction between the energy source and the carbon source, which is characteristic of the above three groups is lost since this group can derive both the carbon and energy from a single organic compound.

	This nutritional classification is arbitrary since some organisms classified as photo. heterotrophs can also grow in dark as chemoheterotrophs. Thus chemoheterotrophy is an alternate nutritional mode of certain photo heterotrophs and chemoautotrophs.

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Growth of Microorganisms Part 2 Carbon Cycle Nitrogen Cycle Sulphur Cycle Chemical Composition of E.Coli Cell Carbon Requirement of Microorganisms Nitrogen & Sulphur Requirement of Microorganisms Microorganisms Classification Based on Oxygen Requirement Microorganisms Nutritional Classificatione Carbon & Energy Source Microorganisms Classification

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