耐热黑曲霉3.316产内切葡聚糖苷酶培养条件优化及酶学性质研究

以内切葡聚糖苷酶的酶活力为指标,采用单因素结合和响应面法对黑曲霉产内切葡聚糖苷酶的培养基组分进行优化,并研究内切葡聚糖苷酶酶学性质。结果表明:最佳培养基组分为小麦秸秆16.29 g/500 mL,硫酸铵2.24 g/500 mL,微晶纤维素+麦芽糖2.16 g/500 mL,在该条件下内切葡聚糖苷酶酶活力4.257 U/mL,优化后的酶活力提高了86%。内切葡聚糖苷酶最适温度是60℃,热稳定性在50℃较高;内切葡聚糖苷酶最适pH值是3,稳定性在5时较高。动力学模型表明以羧甲基纤维素钠为底物的内切葡聚糖苷酶Km=0.0211 mol/L,Vm=0.0036 mmol/min。内切葡聚糖苷酶能够在高温及酸性环境中发挥作用,参与高效降解高温酸性环境中的纤维素,提高其生产率,具有应用高温大曲发酵酒生产的潜力。

Medium Optimization for Endoglucanase Production by Aspergillus niger 3.316 and Its Enzymatic Properties

Endoglucosidase activity was used as an index to optimize the medium composition of endoglucosidase produced by Aspergillus niger and to investigate its enzymatic properties.Results from single factor combination and response surface method on the optimization of the medium conditions for endoglucosidase production by A.niger 3.316 showed that the optimal medium group could be divided into wheat straw 16.29 g/500 mL,ammonium sulfate 2.24 g/500 mL,and microcrystalline cellulose+maltose 2.16 g/500 mL,under an endoglucosidase activity of 4.257 U/mL.Overall,the enzymatic activity increased by 86%compared with that before optimization.The optimal temperature and pH were 60℃and 3,respectively,and the stability of the endoglucosidase was higher at 50℃at pH 5.The kinetic model showed that the endoglucosidase Km and Vm values were 0.0211 mol/L and 0.0036 mmol/min,respectively,using sodium carboxymethyl cellulose as substrate.Hence,the endoglucosidase activity may contribute to the efficient degradation of cellulose in high-temperature and acidic environments.Moreover,endoglucosidase-mediated decomposition of glucose may improve the productivity of wine production via performance of high-temperature daqu fermentation.