2012年9月6日 讯 /生物谷BIOON/ --近日，一项刊登在国际杂志Molecular Microbiology上的研究表明，当细菌在某处聚集的时候，它们会做出一种集体决策来生在某种附属物上或者聚集起来慢慢游走。这种行为首次是在海绵中发现的，这或许可以帮助我们理解如何破坏有害致病菌的生物被膜，比如牙齿斑或者人工心脏中内在医疗设备上的生物被膜。
细菌彼此之间有很多种交流方式，科学家们如今发现了一种新型的信号系统，这种系统可以促使细菌产生诸如鞭毛一样的细菌附属物，使细菌可以自由泳动，并且抑制细菌生物被膜的形成。研究者Hill表示，我们发现的关于细菌交流的任何细节都可以帮助我们理解细菌对于人类是如何进行致病的以及细菌如何在牙齿或者医疗器械内部形成菌膜。理解这个过程将帮助我们有效控制致病菌的生物被膜产生。
细菌可以通过很多途径聚集起来然后形成生物被膜，而且细菌知道如何进行沟通以确定做出机体的决策，从而指导其发生某种行为，这种行为系统成为群体感应系统（quorum sensing）。特殊的海绵包括了复杂和不同的细菌群落，在某些情况下甚至占到了海绵生物量的30%-40%。群体感应系统可以控制细菌细胞一系列的过程，包括引发细菌举起寄来在牙齿上形成菌斑等。
依赖于海绵的细菌，当其细菌数量达到一定程度时，其就可以利用群体感应系统来激活其运动能力，这样就限制了其在固体表面形成生物被膜了。研究者Clay Fuqua说道，细菌的这种行为对于帮助其维持健康、共生的菌群系统非常关键。当然，相同的分子机制或许在别的微生物群落中也会出现，比如人类肠道微生物或者微生物共生植物中等。（生物谷Bioon.com）
编译自：Study: Bacteria on marine sponges can develop capacity to move and inhibit biofilm formation
doi:10.1111/j.1365-2958.2012.08149.x
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A complex LuxR–LuxI type quorum sensing network in a roseobacterial marine sponge symbiont activates flagellar motility and inhibits biofilm formation
Jindong Zan1,†, Elisha M. Cicirelli2,†,‡, Naglaa M. Mohamed1, Hiruy Sibhatu3,§, Stephanie Kroll2,¶, Ohkee Choi2,‖, Charis L. Uhlson3, Christina L. Wysoczinski3, Robert C. Murphy3, Mair E. A. Churchill3, Russell T. Hill1, Clay Fuqua2,*
Bacteria isolated from marine sponges, including the Silicibacter–Ruegeria (SR) subgroup of the Roseobacter clade, produce N-acylhomoserine lactone (AHL) quorum sensing signal molecules. This study is the first detailed analysis of AHL quorum sensing in sponge-associated bacteria, specifically Ruegeria sp. KLH11, from the sponge Mycale laxissima. Two pairs of luxR and luxI homologues and one solo luxI homologue were identified and designated ssaRI, ssbRI and sscI (sponge-associated symbiont locus A, B and C, luxR or luxI homologue). SsaI produced predominantly long-chain 3-oxo-AHLs and both SsbI and SscI specified 3-OH-AHLs. Addition of exogenous AHLs to KLH11 increased the expression of ssaI but not ssaR, ssbI or ssbR, and genetic analyses revealed a complex interconnected arrangement between SsaRI and SsbRI systems. Interestingly, flagellar motility was abolished in the ssaI and ssaR mutants, with the flagellar biosynthesis genes under strict SsaRI control, and active motility only at high culture density. Conversely, ssaI and ssaR mutants formed more robust biofilms than wild-type KLH11. AHLs and the ssaI transcript were detected in M. laxissima extracts, suggesting that AHL signalling contributes to the decision between motility and sessility and that it may also facilitate acclimation to different environments that include the sponge host
