Zn对解淀粉芽孢杆菌JK-JS8生物膜形成及拮抗能力的影响

Biofilm formation and antagonistic ability of Bacillus amyloliquefaciens JK-JS8 under Zn stress

摘要:

【背景】锌（Zn）是一种微量元素，对细菌细胞的结构和调节系统非常重要。细菌在环境中会受到高浓度锌离子影响，进而影响其自身的功能。【目的】研究Zn对解淀粉芽孢杆菌JK-JS8生物膜及拮抗松枯梢病病菌能力的影响，探讨二者之间的联系和可能的作用机制，为生防菌在不同环境条件下的应用提供理论依据。【方法】观察解淀粉芽孢杆菌JK-JS8在不同浓度锌离子条件下生物膜的形成情况，采用平板对峙法探究非致死浓度的锌离子对解淀粉芽孢杆菌JK-JS8拮抗松枯梢病病菌效果的影响，通过RT-qPCR检测ZnCl₂处理后生物膜相关基因的表达，检测抗菌产物的生成情况。【结果】300 μmol/L ZnCl₂对解淀粉芽孢杆菌JK-JS8的生长量无影响，但显著抑制了JK-JS8生物膜形成能力及拮抗病原菌能力。Zn胁迫下，tasA、spo0A和bamD等生物膜相关基因的表达量与对照组相比明显下调，通过液相色谱检测到抑菌产物bacillomycin D的产量在24、48和72 h时分别降低了39.1%、58.8%和61.0%。【结论】环境中的锌离子浓度过高会影响解淀粉芽孢杆菌JK-JS8的生物膜形成，进而降低其拮抗病原菌的能力。

关键词:Zn;解淀粉芽孢杆菌;生物膜;拮抗作用

Abstract:

[Background] Zinc (Zn) is an important trace element for the structure and regulatory system of bacterial cells. In the environment, bacteria exposed to high levels of Zn ions can be affected on their functions.[Objective] To study the effect of Zn on Bacillus amyloliquefaciens JK-JS8 biofilms and its antagonistic ability against Sphaeropsis sapinea, and to explore the possible mechanism between them, so as to provide theoretical basis for the application of biocontrol bacteria in different environmental conditions.[Methods] The formation of B. amyloliquefaciens JK-JS8 biofilms under different concentrations of Zn ions was observed, and the effect of non-lethal concentration of Zn on the antagonistic ability of B. amyloliquefaciens JK-JS8 against S. sapinea was explored by the plate confrontation method. Quantitative reverse transcription-polymerase chain reaction (RT-qPCR) was used to detect the expression of biofilm-related genes and the generation of antibacterial products after the treatment of ZnCl₂.[Results] The concentration of Zn ions at 300 μmol/L had no effect on the growth of B. amyloliquefaciens JK-JS8, but significantly inhibited the formation of its biofilms and the antagonism against pathogenic organisms. Under Zn stress, the expression levels of biofilm-related genes such as tasA, spo0A and bamD were markedly down-regulated compared with the conditions in control group. The production of bacillomycin D decreased by 39.1%, 58.8% and 61.0% at 24 h, 48 h and 72 h, respectively, which was determined by the liquid chromatography. [Conclusion] High concentration of Zn ions in the environment can affect the formation of B. amyloliquefaciens JK-JS8 biofilms and reduce its ability to antagonize the pathogenic organisms.

Key words:Zn;Bacillus amyloliquefaciens;biofilm;antagonism