Alkaline Protease Production by a Strain of Marine Yeasts

摘要

Yeast strain 10 with high yield of protease was isolated from sediments of saltern near Qingdao, China. The protease had the highest activity at pH 9.0 and 45℃ . The optimal medium for the maximum alkaline protease production of strain 10 was 2.5 g soluble starch and 2.0 g NaNO_3 in 100 mL seawater with initial pH 6.0. The optimal cultivation conditions for the maximum protease production were temperature 24.5℃ , aeration rate 8.0 L min~(-1) and agitation speed 150 r min~(-1). Under the optimal conditions, 623.1 U mg~(-1) protein of alkaline protease was reached in the culture within 30 h of fermentation.