高效稻秆降解菌的分离鉴定

Isolation and identification of high-efficiency rice straw degrading bacteria

为实现稻秆快速降解、原位还田,利用秸秆粉平板和刚果红-纤维素平板从土壤中初步筛选出4株降解稻秆能力较强的细菌,进行菌落特征和菌体形态观察;运用DNS法测定4种细菌的纤维素酶活变化曲线,分析稻秆失重率及残渣含量发现其中两株细菌降解效果更优;利用16Sr DNA序列分析鉴定菌属,随后将4株细菌建立复合菌系降解稻秆。结果表明,35℃、180r/min摇床培养15d后发现菌XJ1、XJ2、XJ8、XJ9处理的稻秆降解率分别达到78.04%、72.68%、68.48%和76.58%。菌XJ1为地衣芽胞杆菌属,菌XJ9为高温芽孢杆菌属。37℃、180r/min摇床培养3d后复合菌系稻秆降解率达50.16%,培养7d时稻秆降解率达58.32%。

In order to achieve rapid degradation of rice stalk and in situ to field, four kinds of bacteria with strong ability to degrade rice straw were preliminarily selected from the soil using rice straw powder medium and Congo red-cellulose medium to observe the colony characteristics and morphology. The variation curve of cellulase activities of these four bacteria were determined by DNS method. By analyzing the weight loss rate and residue content of rice straw, two among these bacteria had high ability to degrade. Then using 16SrDNA sequence analysis, the bacteria was identified. In the end, combining these four bacteria, a complex bacterial strain was established to degrade rice straw. The results showed that the degradation rates of rice straw treated with XJ1, XJ2, XJ8 and XJ9 were 78.04%, 72.68%, 68.48% and 76.58% after 15 days of shaking at 35℃ and 180 r/min. Strain XJ1 was identified as Bacillus licheniformis and strain XJ9 was identified as megathermal Bacillus subtilis. Degradation rate of rice straw in the complex bacterial strain reached 43.20% after 3 days, and the rice straw degradation rate reached 49.76% on the 7th day.