新疆木碱蓬(Suaeda dendroides)根际耐盐促生细菌的筛选及鉴定

【背景】新疆是全国最大的盐渍化土壤分布区,土壤盐渍化严重影响作物生长,耐盐促生菌可以有效改善土壤肥力,提高作物抗逆性,促进植物生长,提高土壤利用率。【目的】分离筛选获得木碱蓬(Suaeda dendroides)根际土壤中耐盐促生菌菌株,对优良促生作用的菌株进行分子鉴定,挖掘微生物资源,为微生物菌剂的研制奠定基础。【方法】采用传统的分离方法筛选获得木碱蓬根际耐盐微生物,采用"三级筛选体系"筛选获得耐盐促生菌菌株,用CTAB法提取菌株DNA,对菌株16S rRNA基因测序进行系统发育分析,确定耐盐促生菌菌株的分类地位。【结果】从木碱蓬根际共分离获得耐盐微生物58株,8株具有固氮活性,解磷活性菌株12株,具有解钾活性菌株15株,产IAA活性的菌株3株,具有较强产氨活性的菌株2株。经过促生平板筛选,菌株GTZW50-5和MH-F促进了拟南芥生长,表现出较好的促生效果,通过小麦盆栽试验,菌株GTZW50-5对小麦的根长以及株高具有显著的促生作用,在一定程度上提高了植物体内的叶绿素含量。MH-F菌株对小麦的根系具有较显著的促生作用,且对小麦的叶绿素及脯氨酸含量在不同盐浓度下都有所提高。经过系统发育分析,GTZW50-5与Bacillus vallismortis (AY603658)序列相似度达到99.43%,鉴定属于Bacillus vallismortis,MH-F与Enterobacterludwigii(JTLO01000001)序列相似度为98.34%,鉴定属于Enterobacter属。【结论】菌株GTZW50-5与MH-F均具有较好的促生效果,这为耐盐微生物资源的开发和利用提供了理论依据。

Screening and identification of salt-tolerant promoting bacteria of the rhizosphere of Suaeda dendroides in Xinjiang

Background] Xinjiang is the largest salinized soil distribution area in China. Soil salinization inhibits plant growth seriously. Salt-tolerant promoting bacteria can improve soil fertility, crop stress resistance and soil utilization effectively, thus it promotes plant growth. Objective] We isolated and screened salt-tolerant strains from rhizosphere soil of Suaeda dendroides. The strains with excellent growth-promoting effect were identified, and the microbial resources were excavated. Methods] The traditional method of separation was used to screen the salt-tolerant bacteria in the rhizosphere of S. dendroides. The strains of salt-tolerant promoting bacteria were obtained through the three-stage screening system. DNA of the strains was extracted by CTAB method, and the 16S rRNA gene sequencing was performed for phylogenetic analysis to determine the classification status of the salt-tolerant bacteria. Results] A total of 58 salt-tolerant bacteria were isolated from the rhizosphere of S. dendroides. There were 8 strains with nitrogen fixation activity, 12 strains with phosphate solubilizing activity, and 15 strains with potassium solubilizing activity, 3 strains with IAA activity, and 2 strains with strong ammonia producing ability. Strains named GTZW50-5 and MH-F promoted the growth of Arabidopsis thaliana significantly. The results of wheat pot experiment showed strain GTZW50-5 had significant growth promotion effect on root length and plant height of wheat, and to some extent, the chlorophyll content in plants was improved. Strain MH-F had a significant promoting effect on the roots of wheat, and the chlorophyll content and proline content of wheat were increased at different salt concentrations. According to phylogenetic analysis, the similarity between GTZW50-5 and Bacillus vallismortis (AY603658) was 99.43%, GTZW50-5 was identified as Bacillus vallismortis. The similarity between MH-F and Enterobacter ludwigii (JTLO01000001) sequence was 98.34%, which was identified as Enterobacter. Conclusion] Strains GTZW50-5 and MH-F had a good effect of promoting growth, providing a theoretical basis for the development and utilization of salt-tolerant microbial resources.