锰消除镰刀菌酸对枯草芽胞杆菌R31生物被膜形成的抑制

为了揭示芽胞杆菌类生防因子和镰刀菌病害的互作方式，对镰刀菌酸抑制枯草芽胞杆菌生物被膜形成及其消除开展了研究。首先利用24孔细胞培养板建立了镰刀菌酸抑制枯草芽胞杆菌R31生物被膜形成的生物测定体系，并筛选出抑制R31生物被膜形成所需的最低镰刀菌酸浓度。测定了在该镰刀菌酸浓度处理下的R31生长曲线，并利用显微镜观察了镰刀菌酸处理和对照在振荡培养和静置培养下的菌体形态。然后测定了不同浓度MnSO₄添加消除镰刀菌酸抑制R31生物被膜形成的效果，并用高效液相色谱测定了各处理镰刀菌酸的残留量。结果显示，以24孔细胞培养板为培养容器，以BGM1为培养基的生物测定系统中，显著抑制R31生物被膜形成的最低镰刀菌酸用量为9 μg/mL；该浓度的镰刀菌酸抑制了静置培养的R31菌体形成网状结构和漂浮在液面，并抑制了振荡培养的R31早期菌体增殖。但共培养体系中添加MnSO₄可以恢复R31的生物被膜形成，其中200 μg/mL的硫酸锰不仅能消除毒素抑制，还可显著促进R31的生物被膜形成。镰刀菌酸可能通过影响R31基质产生细胞的分化而抑制其生物被膜形成，硫酸锰可以作为钝化剂缓解镰刀菌酸对R31生物被膜形成的抑制。

Elimination of the Inhibition of Fusaric Acid on the Biofilm Formation of Bacillus subtilis R31 by Manganese

In order to reveal the interaction mechanisms between Bacillus biocontrol agents and plant pathogen Fusarium, the inhibition of fusaric acid (FA) from Fusarium on the biofilm formation of Bacillus subtilis strain R31, and the elimination of the inhibition were investigated. Firstly, a bioassay system was established to test the inhibition of FA on the biofilm formation of B. subtilis R31 by 24-well cell culture plate, and the lowest concentration of FA on the biofilm formation of R31 was screened out. The growth curve of B. subtilis R31 was tested in the presence of the minimum concentration of FA, and the cells of R31 with or without the FA treatment under shaking or static cultivation were observed by microscopy. Then, different concentrations of MnSO₄ were added into the co-cultural system to eliminate the inhibition of FA on the biofilm formation of R31, and the residue of FA in each treatment was determined by HPLC. The results showed that in this bioassay system, 9 μg/mL of FA could drastically inhibit the biofilm formation of R31 by inhibiting its reticular structure formation of R31 cells and reducing the cells floating on the liquid surface in static culture. 9 μg/mL of FA can also inhibit the growth of early-stage R31 in shaking culture. Adding MnSO₄ into the co-culture system, however, can restore the biofilm formation of R31. More specially, 200 μg/mL of MnSO₄ can not only eliminate the inhibition of FA on the biofilm formation of R31, but also significantly promote its formation. FA may inhibit the biofilm formation of R31 by affecting the differentiation of matrix-producing cells of R31, and MnSO₄ can be used as a passivating agent to alleviate the inhibition of FA on the biofilm formation of R31.