古尔班通古特沙漠苔藓结皮土壤中促生菌的分离筛选及促生特性研究

Isolation,Screening,and Growth-Promotion Characteristics of Plant Growth Promotion Microorganisms in Mossy Crust Soil of Gurbantunggut Desert

从古尔班通古特沙漠南缘苔藓结皮土壤中分离筛选植物促生菌并阐明其促生特性,对于发掘和应用功能性微生物制剂,促进植被恢复和提升荒漠固沙能力等具有积极意义。采用富集方法从苔藓生物结皮下0~20 cm土壤中分离可培养微生物。利用选择性培养基筛选具溶磷、产铁载体、分泌吲哚乙酸(IAA)特性的菌株。采用钼锑抗比色法、CAS检测法、Salkowski比色法分别测定菌株溶磷量、产生铁载体的浓度、分泌IAA的含量,并对性能优良的菌株进行分类鉴定。共筛选出促生菌31株,其中溶磷菌31株,产铁载体菌13株,分泌IAA菌28株。菌株LB5WH溶解无机磷能力最强,溶磷量为302.24 mg/L;菌株LB15产铁载体能力最强,产生铁载体的浓度Su值(铁载体活性单位)为85.7%;菌株GA20分泌IAA活性最强,分泌量为15.46 mg/L。菌株LB5WH、LB15同时具有溶磷、产铁载体和分泌IAA活性,菌株GA20具有溶解有机磷、分泌IAA活性。菌株溶解无机磷能力要强于溶解有机磷能力,溶解无机磷菌株的溶磷量与培养液pH值之间呈显著负相关。经鉴定,菌株LB5WH属于芽胞杆菌属(Bacillus),菌株GA20属于寡养单胞菌属(Stenotrophomonas),菌株LB15属于赖氨酸芽胞杆菌属(Lysinibacillus)。这三株细菌的促生功能较多,具有进一步开发为微生物肥料的潜能。本研究为丰富荒漠区促生菌资源,进一步深入研究苔藓结皮下土壤-微生物-植物互作的生态调控机制及荒漠植物促生菌的促生机理提供菌种资源。

Plant growth promoting microorganisms were isolated and screened from mossy crusts in southern fringe of Gurbantunggut desert,and expatiated their growth promoting characteristics and exploring the growth promoting effect has positive significance for exploring and applying functional microbial preparation,promoting vegetation restoration and enhancing desert sand fixation capacity.Culturable microorganisms were isolated subcutaneously from 0 cm to 20 cm soils under the moss biocrusts with the method of enrichment culture.The microbial strains with the ability of phosphate solubilization,siderophores production and indoleacetic acid(IAA)secretion were screened adopting selective media.Then,strains were re-screened by mo-Sb resistance colorimetry,CAS solution and Salkowski colorimetry,respectively for the content of soluble phosphorus,the concentration of iron producing carrier,and the content of IAA,and classified and characterized the strains with excellent performance.The excellent strains were identified by morphological observation,physiological and biochemical characteristics,molecular biological identification.The result showed that 31 growth-promoting strains were screened out,among these 31 strains,31 also were able to dissolve phosphorus,13 also to produce siderophores,28 also to secrete IAA.Strain LB5WH had the highest capacity of dissolving inorganic phosphorus,with dissolving capacity of phosphorus at 302.24 mg/L;strain LB15 had the highest siderophore-producing ability,with producing iron carrier Su value(Siderophore units)at 85.7%;strain GA20 had the highest activity of IAA secretion,with IAA production at 15.46 mg/L.Strains LB5WH and LB15 had the ability of phosphate-solubilizing,siderophores production,and IAA secretion.Strains GA20 had the ability of dissolving organic phosphorus and secreting IAA.And the ability of the strain to dissolve inorganic phosphorus was stronger than that of the strain to dissolve organic phosphorus,and there was a significant negative correlation between the amount of inorganic phosphorus dissolved by the strain and the pH value of culture medium.The identification results of excellent strains showed that strain LB5WH belonged to genus Bacillus,strain LB15 belonged to Lysinibacillus,and strain GA20 belonged to Stenotrophomonas.These three strains had more growth-promoting functions and had the potentials to develop biological fertilizer.The results of this study provided microbial resources for enriching the resources of growth-promoting microorganisms in arid area,further study on ecological regulation mechanism of soil-microbe=plant interaction under the mossy biological crust and the growth-promoting mechanism of desert plant growth-promoting microorganisms.