Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA.
Sci Rep. 2017 May 23;7(1):2277. doi: 10.1038/s41598-017-02628-w.
Microorganisms are key components for plant biomass breakdown within rumen environments. Fibrobacter succinogenes have been identified as being active and dominant cellulolytic members of the rumen. In this study, F. succinogenes type strain S85 was adapted for steady state growth in continuous culture at pH 5.75 and confirmed to grow in the range of pH 5.60-5.65, which is lower than has been reported previously. Wild type and acid tolerant strains digested corn stover with equal efficiency in batch culture at low pH. RNA-seq analysis revealed 268 and 829 genes were differentially expressed at pH 6.10 and 5.65 compared to pH 6.70, respectively. Resequencing analysis identified seven single nucleotide polymorphisms (SNPs) in the sufD, yidE, xylE, rlmM, mscL and dosC genes of acid tolerant strains. Due to the absence of a F. succinogenes genetic system, homologues in Escherichia coli were mutated and complemented and the resulting strains were assayed for acid survival. Complementation with wild-type or acid tolerant F. succinogenes sufD restored E. coli wild-type levels of acid tolerance, suggesting a possible role in acid homeostasis. Recent genetic engineering developments need to be adapted and applied in F. succinogenes to further our understanding of this bacterium.
微生物是瘤胃环境中植物生物质分解的关键组成部分。产琥珀酸丝状杆菌已被确定为瘤胃中活跃且占优势的纤维素分解菌。在这项研究中，产琥珀酸丝状杆菌 S85 型菌株适应在 pH5.75 的连续培养中达到稳定生长，并证实其在 pH5.60-5.65 的范围内生长，这比之前报道的要低。野生型和耐酸菌株在低 pH 下的分批培养中以相同的效率消化玉米秸秆。RNA-seq 分析显示，与 pH6.70 相比，在 pH6.10 和 5.65 时，分别有 268 和 829 个基因差异表达。重测序分析在耐酸菌株的 sufD、yidE、xylE、rlmM、mscL 和 dosC 基因中发现了七个单核苷酸多态性 (SNP)。由于缺乏产琥珀酸丝状杆菌的遗传系统，因此在大肠杆菌中突变和互补了同源基因，并对这些菌株进行了耐酸测定。用野生型或耐酸型产琥珀酸丝状杆菌 sufD 进行互补恢复了大肠杆菌的野生型耐酸水平，这表明其在酸稳态中可能具有作用。最近的遗传工程发展需要在产琥珀酸丝状杆菌中进行适应和应用，以进一步了解这种细菌。
