Improved Citric Acid Production by Radiation Mutant Aspergillus niger Using Sugarcane Bagasse Extract

Due to huge demand of citric acid, attempts are taking to introduce its efficient production either by using low cost substrates or by improving the potency of the fermentation microorganisms. In this study, sugarcane bagasse extract was used for citric acid production using wild type Aspergillus niger CA16 and its radiation mutant 79/20 by submerged fermentation. Fermentation was carried out up to 15 days using 5, 10, 15 and 20% of sugarcane bagasse extract which contained 21.06, 32.60, 43.50 and 53.20 g L-1 sugar, respectively. The fermentation medium was supplemented with prescott salt. With the increasing concentration of baggase extract, total titratable acidity and citric acid production was increased. Moreover, radiation mutant A. niger 79/20 had higher citric acid production than A. niger CA16. Maximum amount of citric acid (12.81 g L-1) was produced in the 20% bagasse extract medium by A. niger 79/20, whereas, CA16 produced 10.25 g L-1 citric acid in the same fermentation medium. Maximum substrate uptake, growth yield co-efficient and productivity were also found higher in case of the strain 79/20. Thus, radiation mutation induced improved citric acid production in A. niger 79/20.