초록
This article reviews the present state of research on the conversion of low cost substrates to citric acid by fermentation. Fermentation is a powerful incentive for semi-industrialized countries. There is a great demand for citric acid due to its wide industrial applications and less toxicity. Citric acid can be produced using less expensive substrates that are renewable too. Plant biomass is one of the desirable raw materials for fermentation due to its availability in abundance. Using natural sources as substrates we can minimize environmental problems. Always species of Aspergillus and Candida remain the choice of candidates for the biosynthesis of citric acid. A concise gist of the various natural sources that can be used for the production of citric acid along with the necessary fermentation conditions is presented.