Anabaena is free-living, nitrogen fixing blue-green alga or cyanobacterium but it may also live symbiotically in the leaf cavities of Azolla, an aquatic, free-floating, fresh water pteridophyte (fern).

Aspergillus niger is used to produce extracellular enzymes such as glucose oxidase, pectinase, -amylase and glucoamylase, organic acids and recombinant proteins. 
Candida lipolytica (Yarrowia lipolytica) produce enzyme lipase.

• Clostridium butylicum (bacterium) produces Butyric acid used for making rancid butter.
• Aspergillus niger (fungus) produces citric acid, employed in dyeing, inks, medicines, flavouring and preservation of food.
• Acetobacter aceti (bacterium) produces acetic acid used in the preparation of vinegar.
• Penicillium (fungi) produces Gluconic acid. Gluconate is the source of calcium to infants, cow and lactating mothers. 

Statins produced by the yeast Monascus purpureus have been utilized as the blood-cholesterol lowering agents. It acts by interfering with the enzyme responsible for synthesis of cholesterol.

Bioremediation is a strategy that uses naturally occurring organisms to break down pollutants, such as petroleum hydrocarbons, into less toxic substances. Species in the bacterial genus Pseudomonas present high potential for hydrocarbon degradation due to their metabolic diversity, their abundance in microbial communities, and their resistance to chemical remediation agents present at contamination sites.

Biological Oxygen Demand (BOD) is a measure of the oxygen used by microorganisms to decompose this waste in the water.

Secondary treatment is the portion of a sewage treatment sequence removing dissolved and colloidal compounds measured as biochemical oxygen demand (BOD). In this stage, the biological processes are used to purify water in a wastewater treatment plants.

Cyanobacteria are autotrophic microbes found widely distributed in aquatic and terrestrial environments. They can fix atmospheric nitrogen also like Anabaena, Nostoc, Oscillatoria, etc.