优良植物根际促生菌的筛选及其生物学特性

Isolation and biological characteristics investigation of superior plant growth promoting rhizobacteria

为获得能应用于环保微生物肥料中性状优良的植物根际促生菌,根据菌株的固氮、溶磷和解钾能力,经过初筛和复筛从不同土壤样本中分离得到1株芽孢杆菌(Bacillus velezensis)(LPL-410.7)。全基因组分析结果显示,该菌株基因组的大小为3907842 bp,GC含量为46.66%,可编码3743个基因/蛋白;生物信息学注释结果显示,LPL-410.7中与促进植物生长相关的功能基因59个,参与次级代谢产物的合成、辅酶运输和代谢、氨基酸运输与代谢等通路途径。进一步的菌株特性试验结果显示,LPL-410.7能够分泌蛋白酶及纤维素酶,并能产生相对表达量为51.78%的铁载体;采用酶联免疫吸附法检测到该菌株亦能产生植物激素吲哚乙酸、赤霉素和细胞分裂素;LPL-410.7在pH 3~10和盐质量浓度为0~15 g/L时均能存活;菌株自凝集性达到88.77%,且具有较强的自由基清除能力。全基因组分析结果与菌株解有机磷、产生促生抗病相关物质(铁载体、吲哚乙酸、纤维素酶和蛋白酶)的实际功能相符合。综合评定,贝莱斯芽孢杆菌LPL-410.7是一株优良的植物根际促生菌,具有很好的开发利用价值。

In order to obtain plant growth promoting rhizobacteria with superior characters that can be applied in environmental friendly microbial fertilizer,a Bacillus velezensis(LPL-410.7)with effective plant growth promoting effect was isolated from different soil samples after preliminary screening and rescreening according to the abilities of nitrogen fixation,phosphorus solubilization and potassium solubilization of strains.Genomic analysis showed that the genome size of the strain was 3907842 bp encoding 3743 genes/proteins and its GC content was 46.66%.The bioinformatics annotation showed that there were 59 functional genes related to growth promotion and biocontrol in LPL-410.7,which are involved in the synthesis of secondary metabolites,transport and metabolism of coenzymes,transport and metabolism of amino acids and other pathways.Further experiments of strain characteristics showed that LPL-410.7 could secrete protease and cellulase and produce siderophores with a relative expression of 51.78%;Enzyme linked immunosorbent assay(ELISA)was used to detect the production of plant hormones indoleacetic acid,gibberellin and cytokinin;LPL-410.7 could survive at pH ranged from 3 to10 and salt concentration ranged from 0 to 15 g/L;The strain had 88.77% self-agglutination and strong scavenging ability of free radical.The results of genomic analysis were consistent with the actual function of the bacterial strain to decompose organophosphorus and produce related substances promoting plant growth(siderophores,indole acetic acid,cellulase and protease).In conclusion,Bacillus velezensis LPL-410.7 is an excellent plant rhizosphere growth promoting bacterium,which has a promising development and utilization value.