Nutritional groups of bacteria

Bacteria are heterotrophic or autotrophic

There are two main groups of autotrophic bacteria; photosynthetic bacteria and chemosynthetic bacteria

Photosynthetic bacteria utilize light energy to build up organic compounds from simple inorganic molecules. They include

Green-sulphur bacteria which obtain hydrogen for reduction of carbon dioxide from hydrogen sulphide or other reduced sulphur compounds and use bacteria chlorophyll to trap light.

Purple sulphur bacteria use hydrogen from hydrogen sulphide and reduced sulphur compounds. They use carotenoids as dominant pigment to trap light

Purple non sulphur bacteria derive hydrogen from organic compounds

Chemosynthetic bacteria

These synthesize complex organic compounds from simple inorganic molecules using energy from oxidation of inorganic compounds

Sulphur – colorless bacteria derive hydrogen and energy from oxidation of hydrogen sulphide, sulphur and other compounds of sulphur

Hydrogen bacteria obtain energy by oxidation of hydrogen

Nitrifying bacteria obtain energy by oxidation of ammonia and nitrite ions

Chemosynthesis bacteria are aerobic; photosynthesizing bacteria are facultative anaerobes

Heterotrophic bacteria obtain energy from living matter through their breakdown activity. E.g. free living parasites and saprophytic bacteria.