盐碱地大豆根内促生拮抗细菌DCX的分离及鉴定

Isolation and identification of an endophytic, antagonistic and growth promoting bacteria DCX from soybean roots in saline-alkali soil

根系内生细菌资源的开发与利用是绿色农业发展的研究重点,而盐碱地大豆根内生细菌的分离与鉴定鲜有报道。本文以大庆盐碱地大豆根系为材料,分离纯化大豆内生细菌,采用平板对峙法和比色法测定内生细菌的抑菌能力和分泌IAA能力,选取抑菌谱广且分泌IAA能力强的株菌,通过检测形态学特征、生理生化性质、结构基因和功能基因序列的系统发育分析,明确细菌的分类地位。结果表明从大庆盐碱地大豆根内分离获得的一株内生细菌DCX,对10种植物病原真菌均具有拮抗作用,其中,对玉米新月弯孢菌、大豆菌核病菌、稻瘟病菌、禾谷镰刀菌的抑菌率分别为50.00%、78.12%、56.25%、43.75%,分泌IAA的能力为2.56±0.41μg·mL-1(n=6)。经形态学、生理生化试验及系统进化分析鉴定,DCX菌株属于解淀粉芽孢杆菌(Bacillus amyloliquefaciens),该菌株在pH11、NaCl浓度10%的NA培养基中生长良好,可为盐碱地的作物病害防治提供资源。

Development and utilization of endophytic bacteria have been the focus of green agriculture,isola tion and identification of endogenous bacteria in soybean root in saline-alkali soil has rarely been reported.In this study,soybean endogenous bacteria were isolated and purified from the soybean root in Daqing saline alkali field by root surface sterilization and grinding.Plate confrontation and colorimetric method were used to measure the ability of bacteriostasis and secreting IAA for selecting strains with wide antimicrobial spectrum and secreting more IAA.Morphological identification,physiological and biochemical analysis,phylogenetic analysis of structural genes and functional genes were used to identify the taxonomic position of isolated bacteria.The results showed that a DCX strain was isolated from soybean roots in Daqing saline alkali field.The strain DCX had the antimicrobial ability to 10 plant pathogenic fungi.The bacteriostasis rates of strain DCX for Curvularia crescent,Sclerotinia Sclerotinia(Lib.)de Bary,Magnaporthe grisea,and Fusarium graminearum Schw were 50.00%,78.12%,56.25%and 43.75%respectively,their ability to secrete IAA was 2.56±0.41μg·mL-1(n=6).DCX strain was identified as Bacillus amy loliquefaciens,and the strain grew well in NA medium under pH11 and salt concentration 10%condition.Their re sults provided resource for prevention and controlling crop disease in saline-alkali soil.