一组耐低温纤维素降解菌系培养条件优化及产酶分析

针对东北寒区冬季沼气发酵水解效率低下问题,从土壤中定向筛选一组耐低温纤维素降解菌系LTF-27。利用间歇试验,通过Box-Benhnken中心组合设计和响应面分析法(RSM),优化其稻秆水解培养条件。反应装置有效体积300 mL,底物唯一碳源为2 g·L~(-1)水稻秸秆,温度控制在(17±1)℃、摇床转速100 r·min-1,培养13 d。通过单因素和中心组合试验确定主要影响因素及优化组合为水稻秸秆2 g·L~(-1),(NH_4)SO_41.5 g·L~(-1),NaCl 5 g·L~(-1),酵母浸粉1 g·L~(-1),MgSO_40.057 g·L~(-1),CaCO_31.49 g·L~(-1),K_2HPO_40.75 g·L~(-1)。优化后低温条件下稻杆降解率可达64.51%,提高10.2%。利用分光光度法对复合菌系LTF-27产酶结果分析表明,该菌系可将纤维素降解为简单糖完整纤维素酶系,酶系中3种关键酶产酶过程相似,β-葡萄糖苷酶酶活(最大值3.4 IU·mL~(-1))较内切葡聚糖酶活(Cx)(最大值8.5 IU·mL~(-1))、外切葡聚糖酶活(C_1)(最大值7.9 IU·mL~(-1))活性低。

Optimization of culture conditions and enzyme analysis of low temperature-resistant cellulose degradation compound strains

Aiming at solving the low efficiency of biogas fermentation hydrolysis in northeast cold region of China,a low temperature-resistant cellulose degrading strains LTF-27 was successfully screened from soil.Batch experiments were performed to investigate the optimal hydrolysis conditions by the method of Box-Benhnken central composite design test and response surface methodology (RSM).LTF-27 was cultured with a working volume of 300mL with rice straw of 2 g· L-1 as sole carbon source.The temperature was maintained at (17±1)℃ and the rotate speed was 100 r· min-1,cultivated 13 d.The optimal straw degradation conditions were determined by single factor experiments and Box-Behnken experiment design.The optimized combination were rice straw 2 g· L-1,(NH4)SO4 1.5 g· L-1,NaCl 5 g· L-1,yeast 1 g· L-1,MgSO4 0.057 g· L-1,CaCO3 1.49 g· L-1,K2HPO4 0.75 g· L-1 The best straw degradation rate was 64.51％,which was 10.2％ higher than that of control.Furthermore,the enzyme activity of compound strain LTF-27 was analyzed by spectrophotometer with time,the results showed that the strains has a complete cellulase system degrading cellulose into simple sugars.The enzymeproducing variation trend was similar and the activity of beta glycosidase (max.3.4 IU· mL-1) was lower than that of Cx (max.8.5 IU·mL-1) and C1 (max.7.9 IU·mL-1).