一株玉米秸秆纤维素降解放线菌的筛选、鉴定及酶学特性研究

Isolation,Identification and Enzymology Characteristics of a Corn Stalk Cellulose-Degradable Actinomycetes Strain

为解决玉米秸秆固废污染和秸秆资源有效利用问题,采用刚果红染色法(水解圈法)和3,5-二硝基水杨酸(DNS)法从玉米秸秆还田土壤中筛选到一株纤维素降解菌,并对该微生物进行生理生化和分子生物学鉴定,发现该菌株降解纤维素效果较好,经鉴定该菌株为纤维素链霉菌(Streptomyces cellulosae),命名为SJS-15,并对该菌株的酶学特性及纤维素降解能力进行了初步研究。结果表明,菌株SJS-15在发酵培养基中的纤维素酶活(CMC)峰值为30.5 U/mL,最适反应pH为6.0,滤纸酶活(FPA)峰值为25 U/mL,最适反应pH为8.0,两种酶均能在温度20~60℃,pH 4.0~10.0范围内保持较高酶活性。纤维素分解实验表明菌株SJS-15对玉米秸秆和滤纸有分解能力,40 d时对玉米秸秆降解率为35.6%(质量分数,下同),对滤纸降解率为18.6%。扫描电镜结果显示经菌株处理的玉米秸秆较对照有明显降解痕迹。菌株SJS-15具有良好的抗逆性和玉米秸秆纤维素分解能力,可作为玉米秸秆还田和堆肥发酵的高效菌株进行进一步研究。

Congo red staining(hydrolysis circle method)and 3,5-dinitrosalicylic acid(DNS)methods were used to solve the problem of solid waste pollution of corn stalk and effective utilization of straw resources,a cellulose degradable strain from corn stalk returning soil was screened.The strain was characterized for its physiological,biochemical,and molecular biology.The results showed that a strain could degrade cellulose relatively effective,and were named as SJS-15,and identified as Streptomyces cellulosae,its enzymatic characteristics and cellulose=degradation ability was initially studied.The results showed that the peak value of cellulase activity(CMC)in the fermentation medium was 30.5 U/mL,the optimal reaction pH was 6.0,the peak value of filter paper enzyme activity(FPA)was 25 U/mL,and the optimal reaction pH was 8.0.Both of the enzymes could maintain high enzyme activities in temperature range of 20-60℃and the pH range of 4.0-10.0.Cellulose degradation experiment showed that strain SJS-15 had decomposition ability to corn stalk and filter paper.The degradation rate of corn straw and filter paper was 35.6%(mass fraction,the same below)and 18.6% at 40 days.Scanning electronic microscopic results showed that the corn straw treated by the strain had obvious degradation traces as compared with the control.Strain SJS-15 has a good resistance and corn stalk cellulose decomposition ability,and can be served as high capability strain for corn straw returning and composting fermentation for further research.