Nazem-Bokaee Hadi, Maranas Costas D
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States.
Front Microbiol. 2018 Aug 24;9:1855. doi: 10.3389/fmicb.2018.01855. eCollection 2018.
The abundance of methane in shale gas and of other gases such as carbon monoxide, hydrogen, and carbon dioxide as chemical process byproducts has motivated the use of gas fermentation for bioproduction. Recent advances in metabolic engineering and synthetic biology allow for engineering of microbes metabolizing a variety of chemicals including gaseous feeds into a number of biorenewables and transportation liquid fuels. New computational tools enable the systematic exploration of all feasible conversion alternatives. Here we computationally assessed all thermodynamically feasible ways of co-utilizing CH, CO, and CO using ferric as terminal electron acceptor for the production of all key precursor metabolites. We identified the thermodynamically feasible co-utilization ratio ranges of CH, CO, and CO toward production of the target metabolite(s) as a function of ferric uptake. A revised version of the iMAC868 genome-scale metabolic model of was chosen to assess co-utilization of CH, CO, and CO and their conversion into selected target products using the optStoic pathway design tool. This revised version contains the latest information on electron flow mechanisms by the methanogen while supplied with methane as the sole carbon source. The interplay between different gas co-utilization ratios and the energetics of reverse methanogenesis were also analyzed using the same metabolic model.
页岩气中丰富的甲烷以及一氧化碳、氢气和二氧化碳等作为化学过程副产物的其他气体，推动了利用气体发酵进行生物生产。代谢工程和合成生物学的最新进展使得对微生物进行工程改造成为可能，这些微生物能够将包括气态原料在内的各种化学物质代谢为多种生物可再生资源和运输液体燃料。新的计算工具能够系统地探索所有可行的转化方案。在此，我们通过计算评估了以铁离子作为终端电子受体，共利用CH₄、CO和CO₂生产所有关键前体代谢物的所有热力学可行方式。我们确定了作为铁离子摄取量函数的CH₄、CO和CO₂用于生产目标代谢物的热力学可行共利用比例范围。选择修订版的iMAC868基因组规模代谢模型，使用optStoic途径设计工具评估CH₄、CO和CO₂的共利用情况以及它们向选定目标产物的转化。这个修订版包含了产甲烷菌以甲烷作为唯一碳源时电子流机制的最新信息。还使用相同的代谢模型分析了不同气体共利用比例与逆甲烷生成能量学之间的相互作用。
