一株多功能秸秆木质素降解菌株的筛选、鉴定及条件优化

Screening, identification and optimization of conditionsfor a multifunctional straw lignin-degrading strain

为实现秸秆资源化利用及提高作物产量,本研究从秸秆中筛选木质素降解菌株,并探究其多种功能,发掘微生物资源的目标。通过菌株苯胺蓝筛选培养、木质素酶活力、IAA能力测定及平板对峙试验等探究菌株促腐、促生及抗病潜能;结合形态学、生理生化特征和16S rRNA序列分析对菌株种属进行鉴定;采用秸秆摇瓶及水稻促生试验测定菌株的实际促腐促生功效;设置单因素试验探究菌株发酵的最适条件。分离筛选的功能菌M15H2鉴定为植生拉乌尔菌(Raoultella planticola)。结果显示,该菌株木质素过氧化物酶活可达129.49 U·mL^(-1),锰过氧化物酶可达23.91U·mL^(-1),漆酶酶活可达8.91 U·mL^(-1)。与对照相比,施用M15H2菌液55 d后秸秆腐解率较对照处理提高32.59%;M15H2产IAA量为3.90 mg·L^(-1),水稻植株发芽率、芽长、根长较对照处理分别增长5.67%、31%和40%;菌液M15H2具有一定的抗水稻条斑病效果,抑菌圈直径与菌落直径的比值为1.20。菌株M15H2发酵的最佳p H为5.0,温度为28~32℃,碳源和氮源分别为蔗糖和酵母粉,装液量是50 mL/250 mL。所筛选的菌株M15H2是兼具促生、抗病作用的多功能秸秆促腐菌,能够加速秸秆降解,促进植株健康生长,具有广泛的开发利用前景。

In order to realize the utilization of straw resources and increase crop yield,this study screened lignin degrading strains from straw and investigated their various functions to explore microbial resources,evaluate the straw degradation,plant growth promotion and disease resistance potential of the strain by combining aniline blue plate screening,lignin enzyme activity,IAA capacity measurement,and plate confrontation test.Strains identification was achieved through morphological,physiological,biochemical,and 16S rRNA sequence analysis;the straw shake bottle test and the rice growth effects of the strain were assessed;a single factor experiment was conducted to determine the optimal conditions for bacterial growth.The straw degrading bacteria isolated and screened were identified as Raoultella planticola.The results showed that the lignin peroxidase activity of strain M15H2 reached 129.49 U·mL^(-1),manganese peroxidase activity reached 23.91 U·mL^(-1) and laccase activity reached 8.91 U·mL^(-1).Compared to the control,the straw decomposition rate was increased by 32.59%after 55 days of application with the M15H2 bacterial liquid.The production of IAA in M15H2 was 3.90 mg·L^(-1),and the germination rate,bud length,and root length values of rice plants increased by 5.67%,31%,and 40%compared to the control,respectively;the bacterial suspension M15H2 had a certain disease resistance effect,and the ratio of the diameter of the antibacterial zone to the diameter of the bacterial colony was 1.20.The optimal fermentation M15H2 were: pH 5.0;fermentation temperature, 28-32 ℃;carbon and nitrogen sources, sucrose and yeast powder, respectively, and the liquid volume, 50 mL/250 mL. The selected strain M15H2 is a straw- promoting and resistant resistance, which can accelerate the degradation of straw and promote the healthy growth of plants, and has a wide prospect of development and utilization.