University of Massachusetts, Amherst, MA, 01003, USA.
University of Nevada, Reno, NV, 89557-0352, USA.
Sci Rep. 2017 Oct 13;7(1):13135. doi: 10.1038/s41598-017-12712-w.
Clostridium ljungdahlii derives energy by lithotrophic and organotrophic acetogenesis. C. ljungdahlii was grown organotrophically with fructose and also lithotrophically, either with syngas - a gas mixture containing hydrogen (H), carbon dioxide (CO), and carbon monoxide (CO), or with H and CO. Gene expression was compared quantitatively by microarrays using RNA extracted from all three conditions. Gene expression with fructose and with H/CO was compared by RNA-Seq. Upregulated genes with both syngas and H/CO (compared to fructose) point to the urea cycle, uptake and degradation of peptides and amino acids, response to sulfur starvation, potentially NADPH-producing pathways involving (S)-malate and ornithine, quorum sensing, sporulation, and cell wall remodeling, suggesting a global and multicellular response to lithotrophic conditions. With syngas, the upregulated (R)-lactate dehydrogenase gene represents a route of electron transfer from ferredoxin to NAD. With H/CO, flavodoxin and histidine biosynthesis genes were upregulated. Downregulated genes corresponded to an intracytoplasmic microcompartment for disposal of methylglyoxal, a toxic byproduct of glycolysis, as 1-propanol. Several cytoplasmic and membrane-associated redox-active protein genes were differentially regulated. The transcriptomic profiles of C. ljungdahlii in lithotrophic and organotrophic growth modes indicate large-scale physiological and metabolic differences, observations that may guide biofuel and commodity chemical production with this species.
产丁酸梭菌通过自养和异养产乙酸获得能量。产丁酸梭菌通过果糖进行异养生长，也可以通过合成气（一种含有氢气 (H)、二氧化碳 (CO) 和一氧化碳 (CO) 的气体混合物）或氢气和一氧化碳进行自养生长。使用从所有三种条件中提取的 RNA 通过微阵列对基因表达进行定量比较。通过 RNA-Seq 比较果糖和 H/CO 条件下的基因表达。与果糖相比，上调的与合成气和 H/CO 相关的基因指向尿素循环、肽和氨基酸的摄取和降解、对硫饥饿的反应、涉及 (S)-苹果酸和鸟氨酸的潜在 NADPH 产生途径、群体感应、孢子形成和细胞壁重塑，表明对自养条件的全局和多细胞反应。在合成气中，上调的 (R)-乳酸脱氢酶基因代表了从铁氧还蛋白到 NAD 的电子转移途径。在 H/CO 条件下，黄素蛋白和组氨酸生物合成基因上调。下调的基因与细胞内微隔间有关，用于处理糖酵解的有毒副产物甲基乙二醛，将其转化为 1-丙醇。几种细胞质和膜相关的氧化还原活性蛋白基因的表达水平存在差异。产丁酸梭菌在自养和异养生长模式下的转录组谱表明存在大规模的生理和代谢差异，这些观察结果可能为该物种的生物燃料和商品化学品生产提供指导。
