Question

What is the mode of nutrition in bacteria?

Answer 1

Two major modes of nutrition in bacteria exist: Autotrophs and Heterotrophs.

Autotrophs are of two types:

1. Photoautotrophs: The bacteria that use light energy, CO₂ as their carbon source and an inorganic electron source (Examples: H₂, H₂S) are called Photoautotrophs
2. Chemoautotrophs: The bacteria that obtain energy by oxidizing inorganic compounds and use CO₂ as their sole source of carbon are called Chemoautotrophs. These include nitrifying bacteria, iron bacteria and sulphur bacteria.

Heterotrophs are of two types:

1. Photoheterotrophs: Bacteria that use light energy and organic electron donors as well as simple organic molecules rather than CO₂ as the source of carbon are called as Photoheterotrophs. These include Purple and Green Bacteria
2. Chemoheterotrophs: Bacteria which use organic compounds as source of energy, electrons, hydrogen and carbon for biosynthesis are called Chemoheterotrophs.