Nutrition in bacteria are either '''autotrophs''' or '''heterotrophs'''.<br> Autotrophic bacteria are again divided into two groups;<br>
Nutrition in bacteria are either '''autotrophs''' or '''heterotrophs'''.<br> Autotrophic bacteria are again divided into two groups;<br>
(i) '''Photoautorophs''' trap solar energy for utilization CO2 and use H2S in place of H2O. Thus, O2 is never released.<br>
(i) '''Photoautorophs''' trap solar energy for utilization CO2 and use H2S in place of H2O. Thus, O2 is never released.<br>
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(ii) '''Chemoautotrophs''' obtain energy from chemical by oxidation process for food synthesis and carbon from CO2.<br> This type include nitrifying bacteria, sulphur bacteria, iron bacteria etc.<br> Heterotrophs are also of two types- Photoheterotrophs and chemoheterotrophs. <br>Photoheterotrophs use light as energy source and an organic compound as source of carbon, e.g. Green and purple bacteria. <br>Chemoheterotrophs use chemical as energy and carbon may also be obtained from the same organic substances.<br> Most of the bacteria belong to this type.
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(ii) '''Chemoautotrophs''' obtain energy from chemical by oxidation process for food synthesis and carbon from CO2.<br> This type include nitrifying bacteria, sulphur bacteria, iron bacteria etc.<br> Heterotrophs are also of two types- Photoheterotrophs and chemoheterotrophs. <br>Photoheterotrophs use light as energy source and an organic compound as source of carbon, e.g. Green and purple bacteria. <br>Chemoheterotrophs use chemical as energy and carbon may also be obtained from the same organic substances.<br> Most of the bacteria belong to this type.<br>