Fang Hao, Toyofuku Masanori, Kiyokawa Tatsunori, Ichihashi Akihiro, Tateda Kazuhiro, Nomura Nobuhiko
Graduate School of Life and Environmental Sciences, University of Tsukuba.
Biosci Biotechnol Biochem. 2013;77(8):1747-52. doi: 10.1271/bbb.130309. Epub 2013 Aug 7.
Bacteria participate in social behaviors by communicating with each other and forming surface-associated biofilms. In Pseudomonas aeruginosa, such social behaviors are affected greatly by the environment. Although P. aeruginosa survive under anaerobic conditions, previous studies indicate that quorum sensing is attenuated under such conditions, and that this leads to decreased activity of extracellular virulence factors as compared to aerobic conditions. Hence it has come into question whether P. aeruginosa are virulent under anaerobic conditions. Here, we compared various phenotypes between PAO1 and clinical isolates under anaerobic conditions. Our data revealed that when grown anaerobically, growth and cell morphology greatly differed among the strains. One of the clinical isolates produced comparable amounts of quorum-sensing signaling molecules and extracellular virulence factors under aerobic and anaerobic conditions, while the other strains showed low production under anaerobic conditions. Biofilm formation also exhibited strain-dependent variations, suggesting that there are several mechanisms that lead to biofilm formation under anaerobic conditions. Taken together, these results indicate that the impact of anaerobiosis on the social interactions of P. aeruginosa is strain dependent, and suggest that multiple regulatory mechanisms are involved in the regulation of quorum sensing and biofilm formation under anaerobic conditions.
细菌通过相互交流并形成与表面相关的生物膜来参与社会行为。在铜绿假单胞菌中，这种社会行为受到环境的极大影响。尽管铜绿假单胞菌能在厌氧条件下存活，但先前的研究表明，群体感应在这种条件下会减弱，并且与需氧条件相比，这会导致细胞外毒力因子的活性降低。因此，铜绿假单胞菌在厌氧条件下是否具有毒性受到了质疑。在这里，我们比较了厌氧条件下PAO1和临床分离株之间的各种表型。我们的数据显示，在厌氧条件下生长时，各菌株的生长和细胞形态差异很大。其中一个临床分离株在需氧和厌氧条件下产生的群体感应信号分子和细胞外毒力因子数量相当，而其他菌株在厌氧条件下产量较低。生物膜形成也表现出菌株依赖性差异，这表明在厌氧条件下存在多种导致生物膜形成的机制。综上所述，这些结果表明厌氧对铜绿假单胞菌社会相互作用的影响具有菌株依赖性，并表明在厌氧条件下，多种调控机制参与了群体感应和生物膜形成的调控。
