Production and properties of an alkaline protease by Aureobasidium pullulans

A strain of the yeast-like fungus Aureobasidium pullulans was grown on whey to produce an extracellular protease. The protease was totally inhibited by the serine inhibitor, phenyl methyl sulphonyl fluoride (PMSF), and partially inhibited by the chelating agent EDTA. The enzyme showed maximal activity in the alkaline range with an optimum pH of 9·5–10·5. The optimum temperature for protease activity was 41C. As well as being active against the non-specific proteolytic substrate Azocoll, the protease readily degraded purified α-casein. A molecular weight of 27000 ± 350 was determined for the protease using gel filtration chromatography.