低温产纤维素酶菌株的筛选、鉴定及纤维素酶学性质

目的]筛选一株低温产纤维素酶菌株并进行鉴定,初步探索其酶学性质,为微生物肥料生产筛选菌种资源.方法]常温条件下,采用CMC-刚果红染色法初筛纤维素降解菌株.采用低温条件诱导的方法,筛选耐低温且产纤维素酶能力最强的菌株,经形态学、生理生化特征试验、ITS序列等方面分析系统分类地位.单因素试验确定温度、pH及金属离子对纤维素酶活力的影响.结果]从秸秆还田土壤中分离出一株在13℃低温环境下高效分解纤维素的真菌M11,鉴定M11为草酸青霉(Penicillium oxalicum).发酵试验表明:以玉米秸秆粉为唯一碳氮源,13℃、200 r/min摇床发酵培养9d时,纤维素酶活力最高为33.08 U/mL.对其酶学性质初步研究表明:该酶最适pH为5.0,最适反应温度为20℃,在5℃-20℃间酶活力仍能保持在90％以上.结论]Penicillium oxalicum M11是一株高效的纤维素降解菌株,在低温条件下可分泌纤维素酶且活性显著,具有潜在的开发价值.

Screening and identification of a cold-adapted cellulase-producing strains and characterization of cellulase

Objective] In order to prepare strains for microbial fertilizer production, a cold-adapted cellulase-producing strain was screened and identified, and its characterization of cellulase was analyzed preliminarily. Methods] CMC-Congo red staining was used to screen the cellulose-degrading strains initially under the condition of normal temperature. Low temperature induction was followed to screen the strain with low temperature resistance and favorable cellulase activity. Then the strain mentioned above was identified by its morphological, the physiological and biochemical properties and ITS sequence analysis. Single factor test based on temperature, pH and metal ions was used to determine the influence of the cellulase activity. Results] Strain M11 producing extracellular cellulose under 13 °C was isolated from the straw returned soil. It was identified as a Penicillium oxalicum. The results of fermentation tests showed that, when corn straw was taken as the only carbon and nitrogen sources, the activity of cellulase was maximum as 33.08 U/mL in the ninth day, under the fermentation conditions of 13 °C, 200 r/min. The results of its cellulase characterization revealed that, the optimum pH was 5.0 and reaction temperature was 20 °C. The relative cellulase activity still reached to 90% in the range of 5 °C?20 °C. Conclusion] The cellulose-degrading strain Penicillium oxalicum M11 could secrete cellulase under the low temperature, and was tremendous potential valuable for microbial fertilizer.