Define Source of Electrons - Growth of Microorganism?

Depending upon the source of electrons used by microorganisms, these are known as -

a) Lithotrophs (rock eaters) - use reduced inorganic substance as electron source.

b) Organotrophs - use electrons from organic compounds.

Microorganisms require a balanced mixture of these elements. Nutritional requirement for different microorganisms vary and can be met through different ways. Microorganisms can be divided into different nutritional types based on their requirement.