产果胶酶菌株的筛选鉴定及产酶条件优化

为了得到产果胶酶菌株,采用含有以果胶为唯一碳源的溴酚蓝平板,结合DP/DC值、平板颜色变化和摇瓶发酵后果胶酶活力的测定等方法进行筛选;对筛选到的菌株XHV25进行菌落形态特征、显微形态结构观察和18S r RNA、ITS、26S r RNA基因序列的测定与分析;通过单因素实验优化菌株XHV25产果胶酶的发酵条件。菌株XHV25的果胶酶活力可达到2937.34 U/m L;经鉴定该菌株XHV25为囊酵母(Zygoascus sp.);其最适发酵产酶条件为:培养基初始p H为5.5,摇床转速为160 r/min,接种量为4﹪(v/v),装液量为25 m L/250 m L,发酵温度为31℃,发酵时间为48 h;在此发酵条件下果胶酶活力为4849.90 U/m L,较优化前显著提高了65.11%。 

Screening and identification of pectinase-producting strains and optimization of pectinase-producting condition

To obtain the pectinase- producing strains, the bromophenol blue plate separation method which contains the pectin as the sole carbon source was used,combined with DP/DCvalue and flat color changes. The strains screened were inoculated for the liquid fermentation culture,and the activities were determinated,then screened again out a strain XHV25 with the pectinase activity of 2937.34 U/m L. Morphology,physiology and biochemistry research coupled with 18 S r RNA,ITS,26 S r RNA sequence and analysis indicates that the strain of XHV25 was Zygoascus sp. Single-factor method was used for optimizing the fermentation condition. The optimum pectinase-producting conditions were as follows :initial medium p H5.5,shaking speed 160 r/min,inoculum amount 4%(v/v),loading volume 25 m L/250 m L,optimum fermentation temperature 31 ℃,fermentation time 48 h.Under this fermentation conditions,pectinase activity reached 4849.90 U/m L,which was 65.11% higher than that of before optimization.