The Effect of Inoculum Size and Medium Volume on Methionine Production by Bacillus species EZ-13 and ZM-10

Abstract

The effect of inoculum size and medium volume on methionine production by Bacillus species EZ- 13 and ZM-10 was studied. The methionine-producing bacteria had already been isolated from within Anambra State University (now Chukwuemeka Odumegwu Ojukwu University), Uli campus Anambra State. They were purified and identified as Bacillus species EZ-13 and ZM-10 using cultural and biochemical characteristics. Thereafter, they were used to evaluated the influence of inoculum size and medium volume on methionine production by Bacillus species EZ-13 and ZM-10 in 250 ml flasks containing 50 ml of sterile fermentation medium. The findings revealed that Bacillus species EZ-13 and ZM-10, at inoculum size of 4% v/v, recorded maximum methionine yields of 2.8 mg/ml and 2.1 mg/ml respectively. The methionine concentrations of both Bacillus species decreased beyond inoculum size of 4% v/v. The medium volume of 50 ml stimulated maximum methionine yield of 3.0 mg/ml in Bacillus species EZ-13 and 2.4 mg/ml in Bacillus species ZM-10. The methionine concentrations for both bacteria decreased beyond medium volume of 50 ml. The result of the study showed that varying the inoculum sizes and medium volumes, could influence methionine yield by fermentation.