Production of Fat and Sterol by Aspergillus nidulans in Submerged Fermentation

Abstract

The efficiency of fat and sterol production by Aspergillus nidulans was evaluated. The fungus was grown in media containing various carbon and nitrogen sources. Some agricultural waste materials namely, corn cob, rice husk and potato peels were also used as sole carbon sources for fat and sterol production. Sodium acetate was added into culture media at various concentrations. After a 72 h incubation, mycelia obtained from culture media were assayed for fat and sterol contents. Among the sole carbon sources used for fat production, the highest yield of 48.63 mg/100 mL broth was achieved with mannitol after 72 h incubation. Carboxyl methyl cellulose was the poorest carbohydrate for fat production. The agricultural waste materials greatly improved fat production by Aspergillus nidulans. Levels of 44.62, 43.99 and 43.1 mg/100 mL broth were achieved with corn cob, rice husk and potato peels after 72 h incubation.  Mannitol also caused the best sterol production by the fungus. Monosodium glutamate and corn steep liquor were the best nitrogen sources for the production of fat and caused the production of 64.36 and 64.27 mg/100 mL broth respectively. Urea and potassium nitrate did not support good fat production by the fungus. Hydrolyzed potato peels supported high yields of sterol as compared to mannitol. Increased fat production was accomplished through the addition of 0.1 to 0.5% sodium acetate. Maximum fat yield of 168.67 mg/100 mL broth occurred after 72 h in medium in which acetate concentration was 0.4%. This level was significantly higher than that of the control which had only 34.82 mg/100 mL broth of fat after 72 h. Acetate addition also caused reasonable increases in sterol synthesis higher than the control.