Abstract:[Background] A fungus producing a neutral protease was isolated from Daqu of Beidacang liquor and identified as Fusarium oxysporim M1 by morphology and molecular biology in our preliminary work. Neutral proteases are important enzyme preparations which have been widely used in industrial production, such as food, medicine, leather, feed, chemical and waste treatment owing to its mild reaction conditions and high catalytic rate. [Objective] In order to apply the neutral protease from Fusarium oxysporim M1 to related industrial production, it is very necessary to purify the protease and study its enzymatic characteristics. [Methods] The protease was purified through ammonium sulfate fractionation, hydrophobic and ion exchange chromatography in this paper, and then its molecular weight was determined by SDS-PAGE electrophoresis. At same time, the thermal stability and acid-base adaptability of the enzyme were also studied. [Results] The protease purification fold and yield were 26.1 and 7.9% by different chromatography steps. The molecular weight of the purified enzyme was 62 kD. The optimum temperature and pH value were 40 °C and 7.0 respectively. The protease belongs to a neutral protease which is sensitive to acid but strong tolerance to alkali. However, it is interesting that the enzyme have strong heat resistance, but is not inhibited by EDTA. [Conclusion] Therefore, the protease from Fusarium oxysporim M1 can be used as a biological catalyst used in different industrial applications in the future.
