Autotrophic Bacteria :
1. The bacteria synthesise their own food.
2. They depend on an external sources of en-ergy for synthesis of food.
3. Autotrophic bacteria live on inorganic substrata.
Heterotrophic Bacteria :
1. The bacteria obtain or-ganic good or organic growth factors from outside sources.
2. An external source of energy is not required.
3. Heterotrophic bacteria live on organic substratum or living host.