一株产吲哚乙酸的Bacillus velezensis JB0319的筛选、鉴定及其促生作用

Screening,Identification and Growth Promotion of A Strain of Bacillus velezensis JB0319 Producing Indoleacetic Acid

【目的】筛选高产吲哚乙酸的促生菌株,分析菌株的功能基因组成和促生潜力,为微生物菌剂的开发利用提供菌种资源。【方法】通过96孔板微培养结合Salkowski比色法筛选青菜(Brassica chinensis L.,pakchoi)根际土壤中具有产吲哚乙酸(indole-3-acetic acid,IAA)能力的根际微生物,并定量复筛高产IAA的菌株。采用形态学、生理生化特征及16S rDNA序列分析方法对菌株进行鉴定,分析菌株在溶磷、产铁载体、产1-氨基羰酰-1-环丙烷羧酸(1-amino-1-cyclopropanecarboxylic acid,ACC)脱氨酶及产生物膜等方面的促生潜力。进一步通过盆栽试验验证其促生效果,从基因组水平初步解析菌株的促生机制。【结果】经鉴定,JB0319是一株贝莱斯芽孢杆菌(Bacillus velezensis),该菌株IAA产量高达30.05μg mL^(−1),具有较强的溶磷、产铁载体、产ACC脱氨酶和产生物膜能力。盆栽试验结果表明,接种JB0319后,青菜的株高、鲜重、根长、根粗和叶片数显著增加,分别较对照增加了17.06%、96.42%、125.77%、50.56%和33.33%。全基因组测序分析表明贝莱斯芽孢杆菌JB0319具有57个与植物促生功能相关的基因。【结论】Bacillus velezensis JB0319可作为候选根际促生菌,为微生物菌剂的开发提供宝贵的菌种资源。

[Objective]After screening,the functional gene composition and growth-promoting potential of the indole3-acetic acid(IAA)-producing strains were analyzed to provide microbial resources for the development and utilization of biofertilizers.[Methods]Screening of IAA-producing pakchoi(Brassica chinensis L.)rhizosphere microorganisms were carried out in 96-well microculture plates using Salkowski reagent,followed by secondary quantitative screening of the strains with high IAA production trait.The isolates were identified by morphological,physiological and biochemical experiments and 16S rDNA sequencing,and the growth promotion potential of them were assayed by phosphorus solubilization,siderophore production,1-amino-1-cyclopropanecarboxylic acid(ACC)deaminase production and biofilm production.The growth promotion effects of the strains were verified by pot experiments.A preliminary analysis of growth promotion mechanism of the strain was conducted at the genome level.[Results]JB0319 was identified as Bacillus velezensis and the IAA yield of JB0319 was up to 30.05μg mL-1.The strain possessed high capacity of phosphorus solubilization,siderophore production,ACC deaminase production and biofilm production.The result of pot experiments showed that inoculation with JB0319 significantly increased the plant height,fresh weight,root length,root diameter and number of leaves of pakchoi by 17.06%,96.42%,125.77%,50.56%and 33.33%,respectively.Whole-genome sequence analysis of JB0319 revealed a total of 57 genes related to growth promotion.[Conclusion]JB0319 can be used as promising PGPR,providing valuable microbial resources for the development of biofertilizers.