Volkers Rita J M, Ballerstedt Hendrik, Ruijssenaars Harald, de Bont Jan A M, de Winde Johannes H, Wery Jan
TNO Quality of Life, P.O. Box 5057, 2600 GB Delft, The Netherlands.
Extremophiles. 2009 Mar;13(2):283-97. doi: 10.1007/s00792-008-0216-0. Epub 2008 Dec 17.
Pseudomonas putida S12 is well known for its remarkable solvent tolerance. Transcriptomics analysis of this bacterium grown in toluene-containing chemostats revealed the differential expression of 253 genes. As expected, the genes encoding one of the major solvent tolerance mechanisms, the solvent efflux pump SrpABC and its regulatory genes srpRS were heavily up-regulated. The increased energy demand brought about by toluene stress was also reflected in transcriptional changes: genes involved in sugar storage were down-regulated whereas genes involved in energy generation such as isocitrate dehydrogenase and NADH dehydrogenases, were up-regulated in the presence of toluene. Several flagella-related genes were up-regulated and a large group of transport genes were down-regulated. In addition, a novel Pseudomonas-specific gene was identified to be involved in toluene tolerance of P. putida S12. This toluene-repressed gene, trgI, was heavily down-regulated immediately upon toluene exposure in batch cultures. The relationship of trgI with solvent tolerance was confirmed by the increased resistance to toluene shock and toluene induced lysis of trgI knock-out mutants. We propose that down-regulation of trgI plays a role in the first line of defence against solvents.
恶臭假单胞菌S12以其显著的溶剂耐受性而闻名。对在含甲苯的恒化器中生长的这种细菌进行转录组学分析，发现253个基因存在差异表达。正如预期的那样，编码主要溶剂耐受机制之一的溶剂外排泵SrpABC及其调控基因srpRS的基因被大量上调。甲苯胁迫带来的能量需求增加也反映在转录变化中：参与糖储存的基因被下调，而在甲苯存在下，参与能量生成的基因如异柠檬酸脱氢酶和NADH脱氢酶被上调。几个与鞭毛相关的基因被上调，一大组转运基因被下调。此外，还鉴定出一个新的假单胞菌特异性基因与恶臭假单胞菌S12的甲苯耐受性有关。这个甲苯抑制基因trgI在分批培养中甲苯暴露后立即被大量下调。trgI基因敲除突变体对甲苯冲击和甲苯诱导裂解的抗性增加，证实了trgI与溶剂耐受性的关系。我们认为trgI的下调在抵御溶剂的第一道防线中起作用。
