Explain the Source of Energy - Growth of Microorganism?

Constant supply of energy is required to carry out cellular activities, like biosynthesis and degradation of macromolecules, transport etc. Two sources of energy are available for microorganisms -

i) Light Energy - Organisms using light as a source of energy are called phototrophs.

ii) Energy derived from organic or inorganic molecules - Organisms using energy obtained by oxidation of organic or inorganic chemical compounds like glucose, H₂S etc. are called chemotrophs.