ISOLATION AND PRODUCTION OF CITRIC ACID BY SOLID STATE FERMENTATION FROM ASPERGILLUS NIGER OF LEMON JUICE
Ajay Kumar*, UshaVerma and Mohsin Nisar Doolwal
Many microorganisms such as bacteria, fungi and yeast can produce citric acid. It is reported that Aspergillus niger is almost exclusively used for industrial scale production of citric acid due to high citric acid productivity at low pH, without secretion of toxic metabolites, ease of handling and ability to ferment a variety of raw materials .For the isolation and production of citric acid three samples taken. i.e. Lemon juice, potato starch and rice starch.7 strains were observed on potato dextrose agar media and LJ3,PS2, RS1 shows growth of A.niger. The isolated strains LJ3,PS2,RS1 were identified by morphological and spore formation to confirm as A.niger. The A.niger strains (LJ3,PS2,RS1*) were selected for citric acid production on PDB. A.niger strain LJ3 gave maximum production of citric acid .i.e.18.2g/ L at 30Oc of144hrs incubation and PS2 gave 6.4g/L and RS1 gave 5.2g/L by SSF. The media optimized for three substrates of citric acid production gave maximum yield by LJ3.ie.10.6g/L, PS2.i.e. 8.1 and RS1 i.e.4.4g/L in selective media of basal media in aerobic conditions.
Keywords: citric acid, Aspergillus niger, ssf.
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