ABSTRACT
A mutant strain RZ13 with high lipase productivity was obtained through treating the Rhizopus sp. RXF12 by UV and microwave,and its activity was 2.62-fold of the original one. The high lipase productivity of the mutant strain could be inherited after repetitious subcultures.The optimal culture conditions of the RZ13 for producing lipase were studied.The lipase with highest activity (67.32U/ml) was obtained on the conditions of 25℃,pH 8.0,5 %(v/v) single spore suspension (1?107spore/ml) and 120 r/min for 84h,and stable under 40℃ and pH 8.5. In addition,the lipase was immobilized by adsorption onto Mg-Al hydrotalcite at 25℃ for 4 h by screening carriers and optimizing the immobilization. The results showed that the optimal reaction temperature and pH were 35~55℃ and 7.5~9.0,respectively,much wider than the free lipase.