The microorganism used for the production of citric acid (HOC(CO2H)(CH2CO2H)2) at the industrial level is Aspergillus niger. Aspergillus niger is a fungus belonging to the division Ascomycota. The fungus causes a fungal disease called “black mold” on many fruits and vegetable plants.
Citric acid (E330) is used widely as a flavoring agent and preservative. James Currie, an American food chemist in 1917 discovered that the fungus Aspergillus niger can be used for the production of citric acid. At the industrial level, the Aspergillus niger grows in glucose or sucrose-containing medium to produce citric acid. Aspergillus niger is also used for the industrial production of gluconic acid (E574).
