Nutrition in Bacteria : Definition, type

Nutrition in Bacteria : Definition, type

On the basis of nutrition, bacteria are of two types-

1. Heterotrophic
2. Autotrophic

Heterotrophic

Chlorophyll is not found in most bacteria, so they take food from plants and animals. On this basis they can be divided into three parts-

1. Parasitic - These bacteria live in the form of parasites on humans and other organisms for the need of food. They spread diseases like typhoid, tetanus, pneumonia, tuberculosis in humans.
2. Saprophytic - These bacteria get their food from nectar organic materials such as rotten matter, leather, food items, pickles, bread, marmalade etc.
3. Symbiotic – Some bacteria live with other plants and animals and benefit each other, it is called symbiosis. And both the organisms that live in this way are called symbiotic. For example, Rhizobium leguminosarum bacteria fix atmospheric nitrogen which is used by plants and in return plants give carbohydrates to bacteria.

Autotrophic

Some bacteria are also autotrophic because they make their own food from carbon dioxide and inorganic substances. These are of two types-

1. Photosynthetic or Photoautotrophic - Some bacteria have chlorophyll-like structures.. Violet and red bacteria contain bacteriopurpurin and bacteriochlorophyll from which they perform photosynthesis, for example- chromatium. Green Bacteria contain Chlorobium Chlorophyll from which they perform photosynthesis, like Chlorobium. Oxygen is not released in this process. This type of photosynthesis is called anoxygenic- without producing oxygen. 
2. Chemoautotrophic or Chemosyntheic Bacteria - These bacteria oxidize some inorganic substances. As a result, the released energy is used in the manufacture of food. These include the following bacteria -

• Nitrifying Bacteria - These bacteria convert ammonia to nitrite, such as Nitrosomonas and Nitrococcus. Nitrobacter bacteria convert nitrite to nitrate.

2NH3  + 3O2 ⟶ 2NO2¯   +  2H⁺  +   2H2O  + Energy

2NO2¯    +    O2  ⟶  2NO3¯  +   Energy 

• Iron Bacteria – These bacteria live in water in which iron compounds are present. It converts ferrous compounds into ferric compounds, e.g. Leptotrix archi.

4FeCO3  +  O2   +  6H2O ⟶ 4Fe(OH)3   +  4CO2   +   Energy 

• Hydrogen Bacteria - These bacteria convert soil hydrogen into methane and water, e.g. Bacillus pantotrophus. Methane, also known as Swamp Gas, is formed in anoxic environments such as the Earth, swamps, and even in the intestines of some humans.

4H2   +  CO2  ⟶  CH4  +  2H2O   +  Energy 

• Sulfur Bacteria - These bacteria convert hydrogen sulfide into water and sulfur. Sulfur gets stored in the cytoplasm, like beziato.

2H2S    +   CO2   ⟶  2S  +   2H2O   +  Energy