Comparative studies on citric acid production by Aspergillus niger and Candida lipolytica using molasses and glucose

Citric acid production by Aspergillus niger NCIM 548 and Candida lipolytica NCIM 3472 has been studied in shake culture using glucose and molasses as carbon sources. Methanol addition (3% v/v) at 40 h of fermentation enhanced the production of citric acid by Aspergillus niger whereas a reduction in citric acid production by Candida lipolytica was observed with addition of methanol. Maximum citric acid concentration of 12 kg/m(3) was obtained with Aspergillus niger using molasses in the presence of methanol, while maximu m citric acid concentration of 8.4 kg/m(3) was obtained with Candida lipoly tica using glucose without methanol. It appears that product formation by A spergillus niger is either nongrowth associated or partially growth associa ted depending on the substrate. Methanol addition changes the nature of pro duct formation in case of Candida lipolytica.