李楚翘, 王天宇, 尹颖, 陈安良, 张心齐, 陈旭华. 盐生植物根际细菌B268的鉴定及其抑菌抗盐活性[J]. 农药学学报, 2022, 24(4): 771-781. DOI: 10.16801/j.issn.1008-7303.2022.0022
    引用本文: 李楚翘, 王天宇, 尹颖, 陈安良, 张心齐, 陈旭华. 盐生植物根际细菌B268的鉴定及其抑菌抗盐活性[J]. 农药学学报, 2022, 24(4): 771-781. DOI: 10.16801/j.issn.1008-7303.2022.0022
    LI Chuqiao, WANG Tianyu, YIN Ying, CHEN Anliang, ZHANG Xinqi, CHEN Xuhua. Identification of a halophyte rhizobacterium B268 and its activity in microbial inhibition and salt tolerance[J]. Chinese Journal of Pesticide Science, 2022, 24(4): 771-781. DOI: 10.16801/j.issn.1008-7303.2022.0022
    Citation: LI Chuqiao, WANG Tianyu, YIN Ying, CHEN Anliang, ZHANG Xinqi, CHEN Xuhua. Identification of a halophyte rhizobacterium B268 and its activity in microbial inhibition and salt tolerance[J]. Chinese Journal of Pesticide Science, 2022, 24(4): 771-781. DOI: 10.16801/j.issn.1008-7303.2022.0022

    盐生植物根际细菌B268的鉴定及其抑菌抗盐活性

    Identification of a halophyte rhizobacterium B268 and its activity in microbial inhibition and salt tolerance

    • 摘要: 为了挖掘耐盐生防菌资源,从盐生植物短枝木麻黄Casuarina equisetifolia L.根际分离获得1株生防细菌B268。采用多相分类法对B268进行鉴定;利用活菌计数和平板对峙法测定菌株的抑菌活性;利用antiSMASH数据库对抗菌物质合成基因簇进行预测;基于氯化钠(NaCl)梯度下的生理活性以及功能基因表达水平检测,分析盐胁迫对菌株生防性状的影响;通过水培试验评估菌株对黄瓜耐盐性的促进作用。结果表明:菌株B268为同种贝莱斯芽孢杆菌群的一个新种系型,在3% (W/V) NaCl下最适生长,生长范围0~15% (W/V) NaCl。共预测到13个抗菌物质合成基因簇,并对9种供试病原菌具有拮抗活性,其中,青枯病菌处理8 h后出现负生长,苹果树腐烂病菌、交替链格孢、胶孢炭疽菌和番茄早疫病菌的平板抑制率均大于60%。在盐梯度培养条件下,B268的胞外嗜铁素和吲哚乙酸浓度分别在1%和3% (W/V) NaCl时最高,而平板溶磷指数保持稳定;吲哚乙酸合成基因dhaS、植酸酶基因phyC在1% (W/V) NaCl,而嗜铁素合成基因dhbC在3% (W/V) NaCl时表达水平最高。接种B268后,水培黄瓜苗对80 mmol/L NaCl胁迫不敏感,对 120 mmol/L NaCl胁迫形成抗性,叶部可溶性糖含量提高46.4%,丙二醛含量降低67.2%。研究表明,B268是1株嗜盐生防菌,具有广谱抗菌活性,且促生活性对盐表现出耦合响应性,在植物盐害、病害生物防治以及盐土生物修复方面具有研发潜力。

       

      Abstract: To tap the resource of halotolerant biocontrol agents, a bacterial strain B268 was isolated from the rhizosphere of halophyte Casuarina equisetifolia L. It was identified based on the polyphasic taxonomic approach. The viable count method and dural culture method were used to assess the antimicrobial activities. Gene clusters related to the biosynthesis of antimicrobial compounds were predicted with antiSMASH. The influence of salt stress on biocontrol traits of B268 was analyzed by checking both the physiological activities and the gene expression levels of cells grown under NaCl gradient conditions. The effect of B268 on plant salt tolerance was evaluated with cucumber seedlings under hydroponic conditions. According to the results of polyphasic identification, strain B268 represents a novel phylotype of the conspecific Bacillus velezensis group. The NaCl concentration (W/V) for growth was 0-15% with the optimum at 3%. Thirteen gene clusters devoted to antimicrobial production were predicted in B268 genome. Nine phytopathogens tested were antagonized by B268, among which negative growth was detected in Ralstonia pseudosolanacearum treated with B268 for 8 hours, and the inhibition rate to Valsa mali var. mali, Alternaria alternate, Colletotrichum gloeosporioides, Alternaria solani were higher than 60%. The concentration of extracellular siderophore and indole-3-acetic acid reached the highest at 1% and 3% (W/V) NaCl, respectively and the phosphate solubilizing index remained stable on the NaCl gradient plates. The expression of indole-3-acetic acid biosynthesis gene dhaS and phytase coding gene phyC were maximally up-regulated at 1% (W/V) NaCl, and siderophore biosynthesis gene dhbC showed the highest expression at 3% (W/V) NaCl. In the hydroponic condition, cucumber seedlings inoculated with B268 were found to be insensitive to 80 mmol/L NaCl and tolerance to 120 mmol/L NaCl, which was illustrated by an increase of soluble sugar by 46.4% and a decrease of malondialdehyde by 67.2% in leaves. In conclusion, B268 is a halophilic biocontrol bacterium with a broad spectrum of antimicrobial activity and its growth-promoting activities show coupling responses to salt. It is suggested that B268 can be used in the biocontrol of plant pathogens or salt stress, as well as in the bioremediation of salinized soils.

       

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