Rossignol Gaelle, Merieau Annabelle, Guerillon Josette, Veron Wilfried, Lesouhaitier Olivier, Feuilloley Marc G J, Orange Nicole
Laboratory of Cold Microbiology, UPRES EA 4312, University of Rouen, 55 rue Saint Germain, 27000 Evreux, France.
BMC Microbiol. 2008 Oct 30;8:189. doi: 10.1186/1471-2180-8-189.
Pseudomonas fluorescens is a ubiquitous Gram-negative bacterium frequently encountered in hospitals as a contaminant of injectable material and surfaces. This psychrotrophic bacterium, commonly described as unable to grow at temperatures above 32 degrees C, is now considered non pathogenic. We studied a recently identified clinical strain of P. fluorescens biovar I, MFN1032, which is considered to cause human lung infection and can grow at 37 degrees C in laboratory conditions.
We found that MFN1032 secreted extracellular factors with a lytic potential at least as high as that of MF37, a psychrotrophic strain of P. fluorescens or the mesophilic opportunistic pathogen, Pseudomonas aeruginosa PAO1. We demonstrated the direct, and indirect - through increases in biosurfactant release - involvement of a phospholipase C in the hemolytic activity of this bacterium. Sequence analysis assigned this phospholipase C to a new group of phospholipases C different from those produced by P. aeruginosa. We show that changes in PlcC production have pleiotropic effects and that plcC overexpression and plcC extinction increase MFN1032 toxicity and colonization, respectively.
This study provides the first demonstration that a PLC is involved in the secreted hemolytic activity of a clinical strain of Pseudomonas fluorescens. Moreover, this phospholipase C seems to belong to a complex biological network associated with the biosurfactant production.
荧光假单胞菌是一种广泛存在的革兰氏阴性菌，在医院中常作为注射材料和表面的污染物被发现。这种嗜冷菌通常被描述为无法在高于32摄氏度的温度下生长，现在被认为是非致病性的。我们研究了最近鉴定出的荧光假单胞菌生物变种I的临床菌株MFN1032，该菌株被认为可引起人类肺部感染，并且在实验室条件下能够在37摄氏度生长。
我们发现MFN1032分泌的细胞外因子具有至少与荧光假单胞菌嗜冷菌株MF37或嗜温机会致病菌铜绿假单胞菌PAO1一样高的溶细胞潜力。我们证明了磷脂酶C直接以及通过增加生物表面活性剂释放间接参与了该细菌的溶血活性。序列分析将这种磷脂酶C归为不同于铜绿假单胞菌产生的磷脂酶C的新组。我们表明PlcC产量的变化具有多效性，并且plcC的过表达和plcC的缺失分别增加了MFN1032的毒性和定殖能力。
本研究首次证明磷脂酶C参与荧光假单胞菌临床菌株分泌的溶血活性。此外，这种磷脂酶C似乎属于与生物表面活性剂产生相关的复杂生物网络。
