腐熟堆肥中维素降解菌筛选鉴定及酶学特性研究

为筛选高效纤维素降解菌,促进堆肥过程中秸秆等纤维素物质快速腐解,在以牛粪和秸秆为材料的腐熟堆肥中分离菌株,以刚果红培养基和滤纸条降解试验初筛菌株,筛选出透明圈与菌落直径比值较大、滤纸条分解能力较强的菌株,作液体发酵培养,测定其酶活力,得到羧甲基纤维素(CMC)酶活和滤纸(FPA)酶活均较高2株菌(1号和7号),并将其在以羧甲基纤维素钠为唯一碳源产酶培养基中作产酶特性研究。结果表明,pH 6.5,培养时间48 h条件下,1号和7号菌株CMC酶活分别为26.82和31.28 U·m L-1,FPA酶活分别为20.32和20.82 U·m L-1。通过形态学、生理生化特征、16S rDNA核酸序列分析及26S rDNA的D1/D2区域测序鉴定,确定1号菌属于枯草芽孢杆菌(Bacillus subtilis),7号菌属于隐球酵母菌(Cryptococcus flavescens)。

Compost isolation and enzymatic characteristics of cellulose-decomposing bacteria

To obtain effective cellulose-decomposing microbe and promote the straw decay rapidly,the strain were isolated from the composting of cow dung and straw as a material by conventional separation.The strain was screened by congo red culture medium and filter paper degrading experiment.The ratio of clear circle to colony diameter was screened.Two strains which had better capacities to decompose cellulose were obtained through determinations of carboxymethyl cellulose activity and filter paper enzyme activity using liquid fermentation.The methods of the optimum cellulose-producing conditions on culture medium,which was isolated with carboxymethyl cellulose sodium as sole carbon source.Through the optimization of culture conditions,it was found that strains 1 and 7 were in the culture medium with the initial pH 6.5,temperature 30 ℃ and after 48 h,the cellulose activity could reach 26.82 and 31.28 U· mL-1,respectively,and the filter paper enzyme activity could reach 20.32 and 20.82 U·mL-1,respectively.Morphological,physiological and biochemical characteristics,16S rDNA nucleic acid sequence analysis and 26S rDNA D1/D2 region sequencing identification showed that the strain 1 was Bacillus subtilis,and the strain 7 was Cryptococcus flavescens.