Metabolite Stress and Tolerance in the Production of Biofuels and Chemicals: Gene-Expression-Based Systems Analysis of Butanol, Butyrate, and Acetate Stresses in the Anaerobe Clostridium acetobutylicum
Metabolite Stress and Tolerance in the Production of Biofuels and Chemicals: Gene-Expression-Based Systems Analysis of Butanol, Butyrate, and Acetate Stresses in the Anaerobe Clostridium acetobutylicum
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DOI：
10.1002/bit.22628
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发表时间：
2010-04-15
影响因子：
3.8
通讯作者：
Papoutsakis, Eleftherios T.
中科院分区：
文献类型：
--
作者：
Alsaker, Keith V.;Paredes, Carlos;Papoutsakis, Eleftherios T.
代谢物积累对细胞生理学具有多效性、毒性或有益作用，但这些作用在分子水平上还没有得到很好的理解。细胞对代谢物应激的反应和适应机制在很大程度上尚未探索，特别是在多重和同时应激的情况下。产溶剂梭菌和相关梭菌对于直接从纤维素材料和其它复合碳水化合物生产生物燃料和化学品具有固有优势，但产物/代谢物耐受性和相关培养物生产率的问题仍然存在。使用DNA微阵列为基础的基因表达分析，丙酮丁醇梭菌发酵酸乙酸和丁酸和溶剂产物丁醇的转录应激反应进行了分析和比较，在细胞生理学的背景下。本体论分析表明，所有三种代谢产物的压力导致上调的基因相关的翻译后修饰和伴侣活性，和下调的防御机制基因。运动基因下调醋酸胁迫。一般代谢物应激包括许多应激基因（dnaK、groES、groEL、hsp90、hsp18、clpC和htrA）、产溶剂操纵子aad-ctfA-ctfB和其他产溶剂基因的上调。乙酸胁迫下调丁酰辅酶A和丁酸盐形成基因的表达，而丁酸盐胁迫下调乙酸盐形成基因的表达。嘧啶生物合成基因被大多数压力下调，但嘌呤生物合成基因被上调的乙酸和丁酸，可能是硫胺素和组氨酸的生物合成。蛋氨酸生物合成基因上调乙酸胁迫，表明可能保守的应激反应机制，也观察到大肠杆菌。固氮基因表达上调乙酸胁迫。丁酸胁迫上调许多铁代谢基因，核黄素生物合成基因，和一些相关的基因，从氧化应激的细胞修复，如perR和超氧化物歧化酶。丁醇胁迫上调甘油代谢基因glpA和glpF。令人惊讶的是，代谢物应激对孢子形成级联基因的表达没有明显影响。有人认为，在响应三种代谢物应激的上调基因的列表包括几个基因，其过表达可能会赋予耐受性，从而使本研究中产生的信息，耐受性重组菌株的发展的一个有价值的来源。Biotechnol. Bioeng. 2010; 105：1131 - 1147. (C)2009 Wiley Periodicals，Inc.
Metabolite accumulation has pleiotropic, toxic, or beneficial effects on cell physiology, but such effects are not well understood at the molecular level. Cells respond and adapt to metabolite stress by mechanisms largely unexplored, especially in the context of multiple and simultaneous stresses. Solventogenic and related clostridia have an inherent advantage for production of biofuels and chemicals directly from cellulosic material and other complex carbohydrates, but issues of product/metabolite tolerance and related culture productivities remain. Using DNA microarray-based gene expression analysis, the transcriptional-stress responses of Clostridium acetobutylicum to fermentation acids acetate and butyrate and the solvent product butanol were analyzed and compared in the context of cell physiology. Ontological analysis demonstrated that stress by all three metabolites resulted in upregulation of genes related to post-translational modifications and chaperone activity, and downregulation of the translation-machinery genes. Motility genes were downregulated by acetate-stress only. The general metabolite stress included upregulation of numerous stress genes (dnaK, groES, groEL, hsp90, hsp18, clpC, and htrA), the solventogenic operon aad-ctfA-ctfB, and other solventogenic genes. Acetate stress downregulated expression of the butyryl-CoA- and butyrate-formation genes, while butyrate stress downregulated expression of acetate-formation genes. Pyrimidine-biosynthesis genes were downregulated by most stresses, but purine-biosynthesis genes were upregulated by acetate and butyrate, possibly for thiamine and histidine biosynthesis. Methionine-biosynthesis genes were upregulated by acetate stress, indicating a possibly conserved stress response mechanism also observed in Escherichia coli. Nitrogen-fixation gene expression was upregulated by acetate stress. Butyrate stress upregulated many iron-metabolism genes, riboflavin-biosynthesis genes, and several genes related to cellular repair from oxidative stress, such as perR and superoxide dismutases. Butanol stress upregulated the glycerol metabolism genes glpA and glpF. Surprisingly, metabolite stress had no apparent effect on the expression of the sporulation-cascade genes. It is argued that the list of upregulated genes in response to the three metabolite stresses includes several genes whose overexpression would likely impart tolerance, thus making the information generated in this study, a valuable source for the development of tolerant recombinant strains. Biotechnol. Bioeng. 2010; 105: 1131-1147. (C) 2009 Wiley Periodicals, Inc.