纤维素降解芽孢菌的筛选及产酶条件优化

为筛选高效的纤维素降解芽孢菌，利用刚果红平板染色法初筛，纤维素酶活性（以滤纸酶活表示）为评价指标进行复筛，从腐木中分离筛选出2株高产纤维素酶菌株K1、K2；结合形态学观察、生理生化特征和16S rDNA基因序列同源性分析，分别鉴定为贝莱斯芽孢杆菌（Bacillus velezensis）、枯草芽孢杆菌（Bacillus subtilis）。对培养条件进行单因素优化和正交试验优化，初步确定菌株K1最佳产酶条件为培养时间3 d，培养温度34 ℃、初始pH值7.0、接种量5%、装液量40%，在此优化条件下滤纸酶活为98.4 U/mL，是优化前的2.1倍。菌株K2最佳产酶条件为培养时间2 d，培养温度34 ℃、初始pH值7.0、接种量6%、装液量为30%，在此优化条件下，滤纸酶活为86.7 U/mL，是优化前的1.8倍。

Screening and enzyme production conditions optimization of cellulose-degrading Bacillus

In order to screen efficient cellulase-degrading Bacillus, using Congo red plate staining method for preliminary screening and cellulase activity (expressed by filter paper activity) for secondary screening, the strains K1 and K2 with high cellulase production were screened from rotting wood. Based on the morphological observation, physiological and biochemical characteristics and the 16S rDNA sequences homology analysis, the strains K1 and K2 were identified as Bacillus velezensis and Bacillus subtilis, respectively. The culture conditions were optimized by single factor experiments and orthogonal experiments. The results showed that the optimum conditions for cellulase production of strain K1 was culture time 3 d, culture temperature 34 ℃, initial pH 7.0, inoculum 5%, loading liquid 40%. The filter paper activity was 98.4 U/ml under the optimal conditions, which was 2.1 times higher than that of before optimization. The optimum conditions for cellulase production of the strain K2 was culture time 2 d, temperature 34 ℃, initial pH 7.0, inoculum 6%, loading liquid 30%. The filter paper activity was 86.7 U/ml under the optimal conditions, which was 1.8 times higher than that of before optimization.