clasify bacteria based on their mode of nutrition
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Classification of Bacteria on the basis of Nutrition
February 11, 2019 by Sagar Aryal
Table of Contents
Nutritional Types of Bacteria
Autotrophic Bacteria
Heterotrophic Bacteria
References
Nutrition is substances used in biosynthesis and energy production and therefore are required for all living things.
Bacteria, like all living cells, require energy and nutrients to build proteins and structural membranes and drive biochemical processes.
Bacteria require sources of carbon, nitrogen, phosphorous, iron and a large number of other molecules.
Carbon, nitrogen, and water are used in the highest quantities.
The nutritional requirements for bacteria can be grouped according to the carbon source and the energy source.
Some types of bacteria must consume pre-formed organic molecules to obtain energy, while other bacteria can generate their own energy from inorganic sources.
Classification of Bacteria on the basis of Nutrition
Nutritional Types of Bacteria
On the basis of energy source organisms are designated as:
Phototrophs:
The organisms which can utilize light as an energy source are known as phototrophs. These bacteria gain energy from light.
Chemotrophs:
These bacteria gain energy from chemical compounds. They cannot carry out photosynthesis.
On the basis of electron source organisms are designated as:
Lithotrophs:
Some organisms can use reduced organic compounds as electron donors and are termed as Lithotrophs.
They can be Chemolithotrophs and Photolithotrophs
Organotrophs:
Some organisms can use organic compounds as electron donors and are termed as organotrophs.
Some can be Chemoorganotrophs and Photoorganotrophs.
Thus, bacteria may be either:
Photo-lithotrops: These bacteria gain energy from light and use reduced inorganic compounds such as H2S as a source of electrons. eg: Chromatium okeinii.
Photo-organotrophs: These bacteria gain energy from light an d use organic compounds such as Succinate as a source of electrons.eg; Rhodospirillum.
Chemo-lithotrophs: These bacteria gain energy from reduced inorganic compounds such as NH3 as a source of electron eg; Nitrosomonas.
Chemo-organotrophs: These bacteria gain energy from organic compounds such as glucose and ammino acids as a source of electrons.eg; Pseudomonas pseudoflora.
Some bacteria can live ether chemo-lithotrophs or chemo-organotrophs like Pseudomonas pseudoflora as they can use either glucose or H2S as electron source.
On the basis of carbon source bacteria may be:
All organisms require carbon in some form for use in synthesizing cell components.
All organisms require at least a small amount of CO2.
However, some can use CO2 as their major or even sole source of carbon; such organisms are termed as Autotrophs (Autotrophic bacteria).
Others require organic compounds as their carbon source and are known as Heterotrophs (Heterotrophic bacteria).
Autotrophic Bacteria
These bacteria synthesize all their food from inorganic substances (H2O, C02, H2S salts).
The autotrophic bacteria are of two types:
(i) Photoautotrophs
These bacteria capture the energy of sunlight and transform it into the chemical energy.
In this process, CO2 is reduced to carbohydrates.
The hydrogen donor is water and the process produce free oxygen.
Photoautotroph has Chlorophyll pigment in the cell and its main function is to capture sunlight e.g., Cyanobacteria.
Some photoautotrophic bacteria are anaerobes and have bacteriochlorophyll and bacteriovirdin pigments respectively.
Purple Sulphur Bacteria:
These bacteria have the pigment bacteriochlorophyll located on the intracytoplasmic membrane i.e., thylakoids. These bacteria obtain energy from sulfur compounds e.g., Chromatiiun. Theopedia rosea, Thiospirilium.
Green Sulphur Bacteria:
These bacteria use hydrogen sulfide (H2S) as hydrogen donor. The reaction takes place in the presence of light and pigment termed as bacteriovirdin or bacteriopheophytin or chlorobium chlorophyll e.g., Chlorobium limicola, Chlorobacterium etc.
These bacteria take hydrogen from inorganic sources like sulphides and thiosulphates. Therefore, these bacteria are also known as photolithographs
Answer:
autotrops and heterotrophs