Citric Acid Production using Induced Mutant Aspergillus niger and Aspergillus awamori Isolated from Soil

This study aimed at citric acid production using mutation induced Aspergillus niger and Aspergillus awamori isolated from soil in Keffi, Nigeria. Soil samples were collected from different location in Keffi. Aspergillus species were isolated and identify using standard microbiological method. Citric acid was produced using a batch fermentation system. Citric acid yield highest by A. awamori A1 was at 30OC with 4.23 mg/l and A. awamori A2 produced highest citric acid 30 OC with 3.93 mg/l whereas A. niger F4 yield highest at 26 OC with 5.03 mg/ml and . A. niger F5 yield the highest at 26OC with 5.75 mg/l. the yield of citric acid at different fermentation duration showed that A. awamori A1 highest after 120hrs with the 5.20 mg/l and A. awawori A2 yield highest after 120hrs with 6.00 mg/l while A. niger F4 yielded 6.09 mg/ml after 144hrs and A. niger F5 produced highest after 144hrs with 6.80 mg/ml. by A. awamori A1 yield highest 5.88 mg/ml at pH of 4.0 and A. awamori A2 produced highest also at pH of 4.0 with 5.84mg/ml. A. niger F4 yields the highest citric acid at pH of 4.5 with 4.99 mg/ml and A. niger F5 yield highest at pH of 4.5 with 7.14mg/ml. A. awamori yields highest at substrate concentrations of 125mg/l with 8.97mg/ml, A. awamori A2 yielded 8.80mg/ml in 150 mg/l substrate concentration while A. niger F4 produced highest in substrate concentration of 175 mg/l with 9.17mg/ml and A. niger F5 yielded highest in substrate concentration of 175 mg/l with 10.02 mg/ml. Strain development will play important role in citric acid and developing strains of Aspergillus species.