芽孢杆菌R1共培养对嗜水气单胞菌NJ-1毒力基因表达的影响

为探讨芽孢杆菌潜在的淬灭靶点,本研究通过芽孢杆菌R1与嗜水气单胞菌NJ-1共培养,并对NJ-1生物量、信号分子产生量、毒力因子基因和群体感应(QS)关键调控基因表达量进行检测。结果显示:1NJ-1单独培养时,信号分子BHL和HHL的产量与NJ-1生长趋势一致,在27 h时达到峰值并启动Lux R表达,进而调控毒力因子金属蛋白酶、丝氨酸蛋白酶、肠毒素、气溶素和血溶素等表达,其在27~30 h时呈现峰值表达,通路Qse B在27~30 h启动表达,48 h时达到峰值,而种间调控Lux S基因表达一直处于低水平状态;2与芽孢杆菌R1共培养时,仅痕量AHLs信号分子被检出,毒力因子相关基因表达量均显著下调;Lux R表达受抑制,Lux S在36 h时表达量显著上调,未影响Qse B正常表达;3AHLs与R1共培养可被显著降解。研究表明,芽孢杆菌R1抑制NJ-1毒力因子相关基因表达可能与其对NJ-1多QS系统进行调控相关联。

Effects of coculture of Bacillus sp. R1 and Aeromonas hydrophila NJ-1 on the virulent factor gene expression of NJ-1

To evaluate the effect of quorum sensing (QS) of Aeromonas hydrophila NJ-1 on modulating pathogenic bacterial virulent factor, NJ-1 was co-cultured with Bacillus sp. R1, a AHLs degrading strain. The results showed that: 1) Under monoculture conditions, the AHL amount of NJ-1 varied with the same trend as the bacteria growth curve. The maximum activity of both AHLs and virulence appeared at 27-30 h, and then decreased with the decline phase. The expression of QseB started at 27 h, and peaked at 48 h, while the expression of LuxS kept at a lower level. 2) Under coculture conditions, AHLs bioactivity was detected only in trace level. Accordingly, the expression of LuxR was not upregulated, and the expression of virulence factors was also distinctly decreased compared to the monoculture. LuxS were upregulated at 36 h, while the expression pattern of QseB was similar as the monoculutre. In conclusion, Bacillus sp. R1 could reduce the virulence of A. hydrophila NJ-1 by the regulatition of the QS of Lux I/R through degrading AHLs activity.