Tomas Christopher A, Beamish Jeffrey, Papoutsakis Eleftherios T
Department of Chemical Engineering, Northwestern University, Evanston, Illinois 60208, USA.
J Bacteriol. 2004 Apr;186(7):2006-18. doi: 10.1128/JB.186.7.2006-2018.2004.
The effects of challenges with low (0.25%, vol/vol) and high (0.75%) concentrations of butanol on the growth, glucose metabolism, product formation, and transcriptional program of the solvent-tolerant Clostridium acetobutylicum strain 824(pGROE1) and the plasmid control strain 824(pSOS95del) were used to study solvent tolerance and stress response. Strain 824(pGROE1) was generated by groESL overexpression. The growth of 824(pGROE1) was less inhibited than that of 824(pSOS95del), and 824(pGROE1) was able to metabolize glucose over the entire course of the culture (60 h postchallenge) while glucose metabolism in 824(pSOS95del) lasted 24 h. A comparison of their respective DNA array-based transcriptional profiles identified genes with similar expression patterns (these genes are likely to be part of a general butanol stress response) and genes with opposite expression patterns (these genes are likely to be associated with increased tolerance to butanol). Both strains exhibited a butanol dose-dependent increase in expression of all major stress protein genes, including groES, dnaKJ, hsp18, and hsp90; all major solvent formation genes, including aad, ctfA and -B, adc, and bdhA and -B (an unexpected and counterintuitive finding); the butyrate formation genes (ptb and buk); the butyryl coenzyme A biosynthesis operon genes; fructose bisphosphate aldolase; and a gene with homology to Bacillus subtilis kinA. A dose-dependent decrease in expression was observed for the genes of the major fatty acid synthesis operon (also an unexpected and counterintuitive finding), several glycolytic genes, and a few sporulation genes. Genes with opposite expression kinetics included rlpA, artP, and a gene encoding a hemin permease. Taken together, these data suggest that stress, even when it derives from the solvent product itself, triggers the induction of the solvent formation genes.
采用低浓度（0.25%，体积/体积）和高浓度（0.75%）丁醇对耐溶剂丙酮丁醇梭菌824(pGROE1)菌株和质粒对照菌株824(pSOS95del)进行挑战，研究其对生长、葡萄糖代谢、产物形成及转录程序的影响，以探讨溶剂耐受性和应激反应。824(pGROE1)菌株是通过groESL过表达构建的。824(pGROE1)的生长受抑制程度低于824(pSOS95del)，并且824(pGROE1)能够在整个培养过程（挑战后60小时）中代谢葡萄糖，而824(pSOS95del)中的葡萄糖代谢仅持续24小时。对它们各自基于DNA芯片的转录谱进行比较，鉴定出具有相似表达模式的基因（这些基因可能是一般丁醇应激反应的一部分）和具有相反表达模式的基因（这些基因可能与丁醇耐受性增加有关）。两种菌株均表现出所有主要应激蛋白基因（包括groES、dnaKJ、hsp18和hsp90）、所有主要溶剂形成基因（包括aad、ctfA和 -B、adc以及bdhA和 -B，这是一个意想不到且违反直觉的发现）、丁酸形成基因（ptb和buk）、丁酰辅酶A生物合成操纵子基因、果糖二磷酸醛缩酶以及与枯草芽孢杆菌kinA具有同源性的基因的表达呈丁醇剂量依赖性增加。主要脂肪酸合成操纵子的基因（这也是一个意想不到且违反直觉的发现）、几个糖酵解基因和一些孢子形成基因的表达呈剂量依赖性降低。具有相反表达动力学的基因包括rlpA、artP以及一个编码血红素通透酶的基因。综上所述，这些数据表明，即使应激源自溶剂产物本身，也会触发溶剂形成基因的诱导。
