Effects of dissolved oxygen concentration and two-stage oxygen supply strategy on the production of γ-CGTase by Bacillus macorous

The effects of different agitation speeds and DO concentrations on γ-CGTase production by Bacillus macorous WSH02-06 were investigated. Higher agitation speeds and DO concentrations were favorable for cell growth but inhibited γ-CGTase production. Lower agitation speeds and DO concentrations were in favor of attaining relatively higher value of specific γ-CGTase production rate in the later stage of fermentation. Two-stage agitation speed control strategy and two-stage DO control strategy were developed and compared for their potential in improving γ-CGTase production. By using the two-stage DO control strategy, γCGTase yield and productivity reached 552.3 U/ml and 6.13 kU/(l h), respectively, increasing by 77.9% and 50.9% over the fermentation at constant agitation speed of 300 rpm.