When agitator speed was 400 rpm and aeration rate was 1.25 vvm, MTG activity reached 5.6 U/mL. It was showed that the level of protease activity could be controlled in the following extraction process.

• 以1.；2 vvm的通气量和400 rpm的搅拌速率；7 L发酵罐最高酶活可达到5