分泌吲哚乙酸的蒌蒿内生耐镉细菌的筛选与鉴定

从蒌蒿（Artemisia selengensis）体中分离分泌吲哚乙酸（IAA）的内生耐镉（Cd）细菌将有助于构建有效的植物-微生物联合修复体系。本研究以分泌IAA和Cd耐性为筛选指标，采用研磨法从蒌蒿的根、茎、叶中分离能产生IAA的内生耐Cd细菌，并对其铅（Pb）、铜（Cu）、锑（Sb）的耐受性及对蒌蒿生长特性的影响进行研究，根据形态特性、生理生化测定和16S rDNA序列分析对目标菌株进行分类鉴定。结果表明，从蒌蒿体内分离获得2株分泌IAA能力较强的内生耐Cd细菌J2和Y5，J2和Y5菌对Cd的耐受质量浓度均为90 mg·L-1，IAA的分泌量分别为23.108、15.192 mg·L-1；J2菌能明显增加蒌蒿的株高、最长根长、平均根长、鲜质量和干质量，Y5菌可显著提高蒌蒿的株高、鲜质量和干质量；J2和 Y5菌对 Pb 的耐受质量浓度均为1200 mg·L-1，对Cu的耐受质量浓度分别为120和160 mg·L-1，对Sb的耐受质量浓度分别为50和150 mg·L-1；J2菌在LB平板上菌落为黄色、近圆形、粘稠，Y5菌在LB平板上菌落为白色、近圆形、湿润；J2和Y5菌的16S rDNA序列经扩增，分别获得1条大小约为1500 bp的条带，经比对分别与GenBank中Pantoea agglomerans STY29（HQ220151）、Pseudomonas fluorescens V7c10（KC195905）的相似性最高，结合形态特征与生理生化特性可分别鉴定为成团泛菌（Pantoea agglomerans）和荧光假单胞菌（Pseudomonas fluorescens）。研究表明，从蒌蒿体中分离获得分泌IAA能力较强的内生耐Cd成团泛菌和荧光假单胞菌，为进一步研究其在蒌蒿修复Cd污染土壤中的作用奠定了基础。

Screening and Identification of Indole Acetic Acid-Producing Cadmium-Resistant Endophytic Bacteria fromArtemisia Selengensis

To isolate indole acetic acid （IAA）-producing cadmium-resistant endophytic bacteria fromArtemisia selengensis is to help build an effective combined remediation system of plant and microorganism. Using IAA-producing and cadmium-tolerance as the screening indexes, isolated IAA-producing cadmium-resistant endophytic bacteria from the root, stem and leafofArtemisia selengensis by the grinding method, and determinated the tolerance of lead, copper, antimony and the effect of the strains on growth ofAremisia selengensis. Strains were identified based on morphological, physiological and biochemical properties as well as 16S rDNA sequence analysis. The results showed that, two cadmium-resistant endophytic bacteria which both have strong abilities to secrete IAA, named as J2 and Y5, were isolated fromArtemisia selengensis. The cadmium tolerance mass concentration of strains J2 and Y5 were up to 90 mg·L-1. The IAA production of strains J2 and Y5 respectively were 23.108 mg·L-1, 15.192 mg·L-1. Strain J2 could significantly increase the plant height, the longest root length, the average root length, the fresh weight and the dry weight of Artemisia selengensis; strain Y5 could significantly improve the plant height, the fresh weight and the dry weight ofArtemisia selengensis. The lead tolerance mass concentration of strains J2 and Y5 were up to 1200 mg·L-1, while the copper tolerance mass concentration of strains J2 and Y5 respectively were 120 mg·L-1 and 160 mg·L-1, the antimony tolerancemass concentration of strains J2 and Y5 respectively were 50 mg·L-1 and 150 mg·L-1. The colony of strain J2 was yellow, suborbicular and sticky on LB tablet. The colony of strain Y5 was white, suborbicular and moist on LB tablet. Strains J2 and Y5 respectively obtained one about 1500 bp band by amplifying 16S rDNA sequences, and by comparing strains J2 and Y5 showed the closest similarity of 16S rDNA sequences to Pantoea agglomerans STY29（HQ220151） andPseudomonas fluorescens V7c10（KC195905） respectively in GenBank and th