No abstract

To enhance the yield and productivity of milkclotting enzyme (MCE) by Bacillus amyloliquefaciens, a two-stage oxygen supply control strategy was proposed and successfully applied in the MCE fermentation. During the first 16 h, K L a was controlled at 72.2 h -1 to obtain high cell growth rate (v) and MCE activity (MCA) productivity (r MCA ). Subsequently, K L a was controlled at 33.9 h -1 to maintain high specific MCA productivity (q MCA ). Using this strategy, MCA peaked at 36 h with the MCA of 6,590.41 SU ml -1 , which was 18 h earlier than other investigated processes. The concept and results described represent the basis of an industrial scale-up process to achieve high MCE yield, MCA productivity and MCA/proteolytic activity.