家蚕肠道纤维素酶菌株的筛选及产酶条件的优化研究

Screening of a Cellulase-producing Strain from the Larval Gut of Bombyx mori and Optimum the Fermentation Condition

从5龄家蚕肠道分离筛选得到一株产纤维素酶菌株BMC-2,以羧甲基纤维素酶(CMCase)比活力为响应值,通过Plackett-Burman试验设计、最陡爬坡试验和Box-Behnken试验设计对菌株BMC-2产纤维素酶发酵条件进行优化,结果表明,发酵时间、发酵温度、培养基初始pH和转速对CMCase比活力具有显著影响,其影响程度由大到小依次为发酵时间、培养基初始pH、发酵温度、转速。确定菌株BMC-2产纤维素酶最优发酵条件为:发酵时间94.35h,发酵温度30.3℃,培养基初始pH7.01,转速179r/min。在此条件下,CMCase比活力理论值为25.801U/mg,验证值为25.526U/mg,较产酶条件优化前提高了1倍,预测模型可靠性高,可应用于菌株BMC-2产纤维素酶条件的优化。

A novel cellulase-producing fungus named BMC-2 was isolated from the fiffh-instar larval gut of Bom- byx mori. Fermentation conditions for the cellulase-producing, in which CMCase specific activity was taken as re- sponse value, were optimized with Plackett-Burman design, steepest ascent test and Box-Benhken design. The re- sults showed that fermentation time, fermentation temperature, initial pH of medium and rotational speed had influ- ence on cellulase-producing significantly. The affecting order was fermentation time, initial pH of medium, fermen- tation temperature and rotational speed, in turn. The optimized fermentation conditions were as follows： fermenta- tion time 94.35 h, fermentation temperature 30.3 ~C, initial pH of medium 7.01 and rotational speed 179 r/min. Under the optimal conditions, the CMCase specific activity was 25.801 U/mg in theory and 25.526 U/mg in actual value that was increased by I times compared with the initial fermentation condition. The result indicated that the established mathematical model by response surface methodology was feasible for practical prediction.