Mn^(2+)促进Bacillus altitudinis LZP02生物膜形成

Mn^(2+)Promotes the Biofilm Formation of Bacillus altitudinis LZP02

【目的】Bacillus altitudinis LZP02是一株水稻根际促生菌(PGPR),能定殖于水稻根部,形成生物膜,且Mn^(2+)对LZP02菌株生物膜形成具有促进作用,但调控机制尚不明确,旨在探究Mn^(2+)对LZP02菌株生物膜形成的促进机制。【方法】采用结晶紫染色法进行生物膜定量分析、蒽酮-硫酸法测定胞外多糖产量、扫描电镜(SEM)观察LZP02菌株在水稻根际定殖情况、转录组学测序技术分析差异表达基因(DEGs)。【结果】添加4 mmol/L Mn^(2+)和8 mmol/L Mn^(2+)显著提高了LZP02菌株的成膜能力和胞外多糖产量,扫描电镜发现4 mmol/L Mn^(2+)和8 mmol/L Mn^(2+)提高了LZP02菌株在水稻根际的定殖能力,随着Mn^(2+)浓度的增加,DEGs数量显著增多,其主要富集在芽孢形成、毒素代谢途径和双组分系统中。1 mmol/L Mn^(2+)和4 mmol/L Mn^(2+)处理组发现skf操纵子中基因的表达均上调。扫描电镜观察发现在1 mmol/L Mn^(2+)和4 mmol/L Mn^(2+)处理组中LZP02菌体存在损伤。4 mmol/L Mn^(2+)处理组双组分系统中KinE和Spo0A基因均显著上调。【结论】Mn^(2+)通过“嗜食同类”和双组分系统中KinE基因激活Spo0A~P提高了菌株LZP02的成膜能力。

【Objective】Bacillus altitudinis LZP02 is a plant growth-promoting rhizobacteria(PGPR)in the rice rhizosphere,which can colonize rice rhizosphere to form biofilm,and Mn^(2+)can promote the biofilm formation of LZP02 strain,but the regulation mechanism is not clear.The purpose of this study is to explore the mechanism of Mn^(2+)promoting the biofilm formation of LZP02 strain.【Method】Crystal violet staining and anthrone-sulfuric acid method were used to perform quantitative analysis of biofilm and exopolysaccharide yield,respectively.Scanning electron microscope(SEM)was used to observe LZP02 colonization in rice rhizosphere.And differently expression genes(DEGs)were analyzed by transcriptome sequencing technology.【Result】The addition of 4 mmol/L Mn^(2+)and 8 mmol/L Mn^(2+)significantly enhanced the film-forming ability of LZP02 strain and the production of exopolysaccharide,scanning electron microscopy showed that 4 mmol/L Mn^(2+)and 8 mmol/L Mn^(2+)improved the colonization ability of LZP02 strain in rice rhizosphere.The number of DEGs increased significantly with the increase of Mn^(2+)concentration,which was mainly enriched in spore formation,toxin metabolism pathway and two-component system.The expression of skf operon gene was up-regulated in 1 mmol/L Mn^(2+)and 4 mmol/L Mn^(2+)treatments.Scanning electron microscope observation showed that there was damage in LZP02 cells in 1 mmol/L Mn^(2+)and 4 mmol/L Mn^(2+)treatments.The genes of KinE and Spo0A in the two-component system of 4 mmol/L Mn^(2+)treatment group were significantly up-regulated.【Conclusion】Mn^(2+)can improve the biofilm-forming ability of strain LZP02 by“cannibalism”and KinE gene activates Spo0A~P in two-component system.