黑胸散白蚁肠道具内切葡聚糖酶活性共生菌的筛选、鉴定及产酶条件的优化

Screening,identification and culture condition optimization of an endoglucanase-producing strain from Reticulitermes chinensis Snyder

目的从黑胸散白蚁肠道内筛选获得具有降解纤维素性能的菌株,并对菌株最佳产酶条件进行优化。方法采用筛选性培养基进行筛选,通过培养性状、显微观察及16S rDNA部分片段同源性分析进行菌种鉴定,利用正交试验优化该菌株的最佳产酶培养基配方以及单因子试验优化产酶培养条件。结果通过鉴定,获得的菌株属柠檬酸杆菌属(Citrobacter sp.B03),最适产酶的碳氮源为CMC-Na和蛋白胨。该菌株最佳产酶培养基的配方为CMC-Na5.0 g/L、蛋白胨5.0 g/L、NH4Cl 0.6 g/L、KH2PO4 0.9 g/L、MgSO4 0.9 g/L;最佳产酶培养条件为起始pH 5.0,温度35℃,装液量20～30 mL/150 mL。结论经过优化,可将该菌株产生的纤维素酶酶活力从0.184 U/mL提高到0.311 U/mL,该研究结果对纤维素酶的工业开发具有一定的指导意义。

Objective To obtain strains with cellulose degradation ability from the digestive tract of Reticulitermes chinensis Snyder and optimize the culture conditions for bacteria enzyme production.Methods Screening medium was used for isolation of endoglucanase-producing bacteria and the result of strain identification was based on microscopic observation,culture characteristics and phylogenetic analysis of 16S rDNA PCR.The optimal medium for endoglucanase production was optimized by orthogonal test and optimal conditions were optimized by single factor test.Results Strain B03 with activity of endoglucanase was identified as Citrobacter.The optimal carbon source and nitrogen source for enzyme production were CMC-Na and peptone.The optimal medium for enzyme production was composed of CMC-Na 5.0 g/L,peptone 4.0 g/L,NH4Cl 0.6 g/L,KH2PO4 0.5 g/L and MgSO4 0.9 g/L.The optimal enzyme-producing conditions were initial pH 5.0,35 °C and liquid volume 20-30 mL per 150 mL shake flask.Conclusion After optimization,the enzyme activity can reach up to 0.311 U/mL from 0.184 U/mL.The result of this study has certain guiding significance to industrialization of cellulose.