*Decay of organic substance reducing them to simple form such as nitrates, sulphates and phosphates. Thus increasing soil fertility.

*Nitrification, in which proteins in dead plants and animals are converted into ammonium compound and oxidized to nitrate and nitrate available for plants.
*Nitrogen fixation  in which atmospheric nitrogen is fixed by N-fixers like Azotobacter, Clostridium and Rhizobium.
*Fertilizer production in which cow dung, animal excreta are converted into manures, and formation of humus are due to action of bacteria.
*Eubacteria in the intestine sythesize vitamins absorbed by the body which aid in digestion of certain materials.
*In industry, manufacturers use cultured bacteria to synthesize some compounds such as acetic acid (vinegar) by Acetobacter, Aceti, Acetone, butanol, lactic acid by lactobacillus and several vitamins.
*Bacteria used in retting of flax and hemp for use in making linen and other textile and rope.
*Commercial preparation of skin for making leather goods.
*In making diary products such as butter and cheese.
*Curdling of milk by lactic acid bacteria.
*Making silage for cattle feed.
*Bacteria pathogenic to certain insect may be used as control methods to replace ibsecticides.
*Production of antibiotics, such as streptomycin, aurcomycin, terramcin, neomycin which are derived from species of actinomyces.
*Genetic engineering research e.g E coli
*production of certain enzymes and other substances e.g insulin
*Intestinal balance of bacterial flora is essential for normal health.