RESUMO
Aims: To improve the cultural conditions for enhanced methionine production by Bacillus cereus S8 Study design: Study of the fermentation process in shake flask culture. Place and Duration of Study: Department of Applied Microbiology and Brewing, Nnamdi Azikwe University, Awka, Nigeria between 2011 to 2012. Methodology: The effects of medium/fermenter volume ratio, carbon and nitrogen sources, growth stimulators, vitamins and amino acid on methionine accumulation in the broth culture of Bacillus cereus S8 were investigated. The time course for methionine production was also studied. Results: A 20% medium/fermenter volume ratio improved methionine yield. Glucose and ammonium sulphate at 6.0 and 1.0% respectively stimulated methionine accumulation by Bacillus cereus S8. Yeast extract, peptone, DL-leucine and all vitamins studied enhanced methionine production. A methionine yield of 3.23mg/ml was produced after 96h fermentation and at a pH of 6.90. Conclusion: Improving the cultural conditions of Bacillus cereus S8 in submerged medium stimulated methionine increase.