棉秸秆纤维素降解菌系构建及固体发酵条件优化

【目的】构建棉秸秆降解菌系及其固体发酵条件优化。【方法】根据羧甲基纤维素酶活(CMC)和滤纸酶活(FPA)筛选纤维素降解能力强的菌株,与调节发酵品质的菌株配比,采用响应面法评价初始含水量、接种量、发酵天数及其交互作用对棉秸秆纤维素降解率的影响。【结果】得到24株纤维素降解菌,其中一株透明圈直径与菌落直径的比例最大值 6.20,FPA酶活力9.699 U/h,CMC酶活力10.435 U/h,通过鉴定为枯草芽孢杆菌(bacillus subtilis),与产朊假丝酵母(Candida utilis)、植物乳杆菌(lactobacillus plantarum)、地衣芽孢杆菌(Bacillus licheniformis)构建复合菌系按1∶1∶2∶1进行发酵,对模型进行方差分析,方程回归显著(P<0.000 1),接种量15.0%,发酵时间35.0 d,水分80.0%时,纤维素降解率达35.91%,接种量对纤维素降解率影响最大。【结论】构建了棉秸秆纤维素降解菌系,确定了固体发酵最佳条件,为棉秸秆饲料化提供了实验及理论依据。

Construction of Cellulose Degrading Strain of Cotton Straw and Optimization of Solid Fermentation Conditions

【Objective】 To construct cotton straw degrading strains and optimize their solid fermentation conditions.【Method】 The cellulose degrading strains were screened based on carboxymethyl cellulase (CMC) and filter paper activity (FPA), and mixed with bacteria strain to adjust the fermentation quality and identify the symbiotic strains mixing ratio, then, the effect of the initial moisture content, inoculation amount, fermentation time and their interactions on cotton stalk cellulose degradation rate were evaluated by using a response surface method.【Result】 24 strains of cellulolytic strain bacteria were obtained, among which, the maximum ratio of the diameter of one transparent circle to the diameter of colony was 6.20, the enzyme activity of FPA was 9.699 U/h, and the enzyme activity of CMC was 10.435 U/h. The strain was identified asbacillus subtilis, which was mixed with J1 (Candida utilis), J2 (Lactobacillus plantarum), J3 (Bacillus licheniformis) to construct composite strains at the ratio of 1∶1∶2∶1 for fermentation. The results of variance analysis showed that the regression equation was significant (P < 0.0001), inoculation amount was 15.0%, fermentation time was 35 days, water content was 80.0%, cellulose degradation rate was 35.91%, the effect of inoculation amount on cellulose degradation was the most significant.【Conclusion】 In this experiment, the cellulose-degrading strain of cotton straw was constructed, and the optimum conditions of solid fermentation were determined, which provided the experimental and theoretical basis for the feed conversion of cotton straw.