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

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

【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。

[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 16 S r RNA 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.