海绵共栖细菌NJ6-3-1基于群体感应调控的抗菌活性

[目的]选择一株海绵共栖细菌Pseudoalteromonas sp.NJ6-3-1,研究其抗菌物质的代谢是否受到群体感应的调控.[方法]我们研究了在不同生长条件细菌NJ6-3-1代谢物的抗菌活性与细胞密度的关系;通过模拟自然的竞争环境,研究了低密度条件下的细菌NJ6-3-1与外源细菌Staphylococcus aureus共培养时的抗菌活性情况.[结果]实验发现细菌NJ6-3-1代谢抗菌物质的行为与细胞密度密切相关,只有当细胞密度达到一定的阈值OD630=0.4时,NJ6-3-1才能代谢抗菌物质;同时发现外源病原菌S.aureus代谢产物中存在某种信号分子,能诱导NJ6-3-1在不产生抗菌物质的生长条件下代谢抗菌物质.[结论]以上结果初步说明NJ6-3-1的抗菌活性受到种内和种间群体感应系统的调控.

Antibacterial Activity of Sponge Associated Marine Bacterium Pseudaltero-monas sp.NJ6-3-1 Regulated by Quorum Sensing

[Objective] We chose a sponge-associated marine-bacterium Pseudoalteromonas piscicida NJ6-3-1 to study whether its antibacterial activity were regulated by quorum sensing. [Methods] We studied the relationship between the antibacterial activity and bacterial density under various growth conditions. To simulate the natural competitive environment, we monitored the antibacterial activity at low cell density when the species were co-cultured with Staphylococcus aureus. [Results] Antibacterial activity correlated closely with cell density. Marine bacterium NJ6-3-1 started producing antibacterial compounds when cell density reached the threshold value of OD630=0.4. Some signal molecules existing in the metabolites of S. aureus could induce the production of antibacterial substance by marine-bacteria NJ6-3-1 even cell density below the required threshold. [Conclusion] The results provide preliminary evidence to support the hypothesis that the antibacterial activity of NJ6-3-1 was regulated by the quorum sensing system of intraspecies and interspecies.