黄芪根际促生菌(PGPR)筛选与特性研究

为获得黄芪根际PGPR菌株并明确其促生特性,可为其在生产中的应用提供依据,本研究以黄芪的根瘤、根系及根际土壤为材料,利用选择性培养基分离筛选根瘤菌与溶磷菌,测定根瘤菌固氮酶活性、溶磷菌株的溶磷能力及分泌3-吲哚乙酸(IAA)的能力,从中筛选出综合性能优良的菌株,并运用生理生化鉴定和16S rDNA分子生物学鉴定相结合的方法鉴定优良菌株的种属。结果发现,溶磷菌数量的分布具有根系表面(RP)>根表土壤(RS)>远根土(NRS)>根内(HP)的规律,有明显的根际效应;经分离纯化获得76 株PGPR菌,其中根瘤菌1株、溶解无机磷菌株42 株和溶解有机磷菌株33 株,其中可分泌IAA能力的溶磷菌株有7株;筛选出综合性能优良,有进一步开发应用潜力的溶磷菌株7株,根瘤菌1株,经鉴定溶磷菌中3株为Pseudomonas sp.,3株为Bacillus sp.和1株为Klebsiella oxytoca,根瘤菌为Rhizobium sp.,这为研制生物菌肥提供优良菌种,同时丰富优良根际促生菌资源库。

Identification of plant growth promoting rhizobacteria Astragalus membranaceus and their effectives

In order to obtain and study the performance of plant growth promoting rhizobacteria (PGPR)in As-tragalus membranaceus ,the root nodule,root morphology and rhizosphere soil of A.membranaceus were col-lected.Strains of rhizobium and phosphate solubilizing bacteria were isolated and assessed for the potentially useful characteristics of high nitrogenase activity in the rhizobium and high phosphate solubilisation and ability to secrete 3-indoleacetic acid (IAA)in the phosphate solubilizing bacteria.Potential PGPR strains were then i-dentified using physiological and biochemical characteristics and 16S rDNA sequence analysis.Results showed there are large amounts of phosphorus-dissolving bacteria in the rhizospheres of A.membranaceus .The quan-titative distribution of bacteria and PGPR shows a strong rhizosphere effect,with rhizosplan or surface of roots (RP)>soil adhering to roots (RS)>soil away from roots (NRS)>histoplan or interior of roots (HP).We have isolated 76 PGPR strains,composed of 1 rhizobium,42 inorganic phosphate solubilizing and 33 organic phosphate solubilizing bacteria strains.There are 7 phosphate solubilizing strains with the ability to secrete IAA.A further 8 potential PGPR strains were identified (1 rhizobium and 7 phosphate solubilizing).3 phos-phate solubilizing strains were identified as Pseudomonas sp.,3 phosphate solubilizing strains as Bacillus sp., 1 phosphate solubilizing strain as Klebsiella oxytoca ,1 rhizobium strain as Rhizobium sp.This study has iden-tified potential PGPR for the development of microbial fertilizers for A.membranaceus .