一株烟草秸秆降解菌的分离、鉴定及酶学性质研究

从皖南地区烟稻轮作田土壤中经CMC-Na初筛获得5株纤维素降解菌,经DNS法测定纤维素酶活性复筛得到一株降解活性较高的降解菌YC-2。根据该菌16S r DNA序列比对结果,结合形态和生理生化特征,确定YC-2为枯草芽孢杆菌(Bacillus subtilis)。对YC-2酶学性质进行相关研究,并分析YC-2对烟碱的耐受情况及对烟草秸秆的降解情况,结果表明:在7天内,YC-2对烟草秸秆降解率为10.14%;酶学特性表现为最适反应温度为60℃且在15~60℃之间具有稳定性;最适反应pH为7.0,在pH 4.0~7.5范围内稳定性较好;YC-2在浓度为1~2 g/L烟碱中能快速生长,而在高浓度的烟碱中生长受到抑制。因此,菌株YC-2产纤维素酶活性较高、相对耐热耐碱且对烟杆有一定分解作用,通过进一步诱变选育和发酵条件优化有较好的田间应用潜力。

Isolation, Identification and Enzymatic Property of a Tobacco Straw Degradation Strain

To obtain microorganism strains for degrading tobacco straws, a strain named YC-2 was screened from a tobacco-rice rotation field in south of Anhui Province using CMC-Na medium and measuring cellulose activity. The train was identified asBacillus subtilisbased on itsphysiological and biochemical characteristics and 16s rDNA analysis.The enzymatic properties of the strain and degradation rate of tobacco straws by the strain were investigated. The effects of neonicotinoids concentration on the growth of YC-2 were also examined. The results indicated that the strain degraded 10.14% of the tobacco straw within 7 days. The optional temperature and pH were 60℃ and 7.0 for the enzymatic reactions of the strain, respectively. The CMCase and FPase were stable in the range of temperature from 15 to 60℃ and at pH from 4.0 to 7.5. The low neonicotinoids concentration of 1–2 g/L promoted YC-2 growth, while high concentration of neonicotinoids would inhibit the growth of the strain. Therefore, this strain has high activity for cellulase production and good tolerance to heat and alkali, and can decompose tobacco straw. Potential application in fields can be realized by further mutation breeding and fermentation condition optimization of the strain.