可可西里豆科植物根瘤内生细菌系统发育及促生特性研究

Study on the Phylogeny and Growth Promoting Effect of Endophytes Isolated from Legume Root Nodules in Hoh Xil

[目的]研究可可西里豆科植物根瘤内生细菌系统发育、抗菌特性和分泌IAA能力。[方法]对分离自可可西里的豆科植物Oxytropis falcate Bunge的根瘤内生细菌进行了16S r DNA全序列分析、抗菌试验以及IAA分泌能力检测。[结果]16S r DNA全序列分析结果表明,17株供试菌有12株属于芽孢杆菌属(Bacillus);有1株供试菌CNU097903与短杆菌属Brevibacterium halotolerans处于同一分支,相似性达99.9%;菌株CNU097916与Agrobacterium tumefaciens处于同一分支,相似性达99.8%;菌株CNU097914和CNU097915处于一个单独的分支,其系统发育地位有待进一步确定。抗菌试验结果表明,10株供试菌对G-黄单胞杆菌(Xanthomonas Campestris)、G+金黄色葡萄球菌(Staphylococcus aureus)、番茄灰霉(Botrytis cinerea)和瓜果腐霉(Pythium aphanidermatum)4种指示菌表现出不同程度的抗性:菌株CNU097906抗菌谱最广,对4种指示菌都有抗性;菌株CNU097902对番茄灰霉的抗性最强,抑菌圈直径达38 mm;菌株CNU097908对黄单胞杆菌的抗性最强,抑菌圈直径达38 mm;菌株CNU097901对金黄色葡萄球菌的抗性最强,抑菌圈直径达41 mm。采用Salkowski比色法测定供试菌分泌IAA的能力,结果表明,10供试菌都具有分泌IAA的能力。[结论]该研究为进一步探究内生细菌的生防机制和途径奠定基础,为可可西里内生菌资源的研究和合理开发利用提供理论依据。

Objective] The aim was to study the phylogeny,antimicrobial activity and secreting IAA capacity of endophytes isolated from legume root nodules in Hoh Xil.[Method] The endophyte strains isolated from the nodules of Oxytropis falcate Bunge in Hoh Xil were used to do the 16s sequences analysis,antimicrobial test and IAA detection.[Result] The result of 16s rDNA sequence analysis showed that 12 of 17 test strains be-long to Bacillus.CNU097903 and Brevibacterium halotolerans,CNU097916 and Agrobacterium tumefaciens were at the same branch respectively , which similarity were as high as 99.9%and 99.8%.CNU097914 and CNU097915 were in a separate branch and their system development status remained to be further confirmed.The antimicrobial experiment result showed that 10 strains had the different degrees of resistance to Xan-thomonas campestris,Staphylococcus aureus,Botrytis cinerea,and Pythium aphanidermatum.CNU097906 had the highest resistant spectrum which could resist to all 4 indicator bacteria.CNU097902 and CNU097908 had the strongest resistance to Botrytis cinerea,Xanthomonas campestris re-spectively and the bacteriostatic circle of 38 mm in diameter.CNU097901 had the strongest resistance for Staphylococcus aureus,and the bacterio-static circle of 41 mm in diameter.The Salkowski colorimetric method showed that all the 10 selected strains had the ability to secrete IAA.[Con-clusion] The study lays a foundation for further research on prevention mechanism and ways of endophytic bacteria ,provides theoretical basis for research of endophytic bacteria in Hoh Xil and rational decelopment .