PDF(Pubmed)
Abstract：
A new variant of Methanothermobacter wolfeii was isolated from an anaerobic digester using enrichment cultivation in anaerobic conditions. The new isolate was taxonomically identified via 16S rRNA gene sequencing and tagged as M. wolfeii BSEL. The whole genome of the new variant was sequenced and de novo assembled. Genomic variations between the BSEL strain and the type strain were discovered, suggesting evolutionary adaptations of the BSEL strain that conferred advantages while growing under a low concentration of nutrients. M. wolfeii BSEL displayed the highest specific growth rate ever reported for the wolfeii species (0.27 ± 0.03 h-1) using carbon dioxide (CO2) as unique carbon source and hydrogen (H2) as electron donor. M. wolfeii BSEL grew at this rate in an environment with ammonium (NH4+) as sole nitrogen source. The minerals content required to cultivate the BSEL strain was relatively low and resembled the ionic background of tap water without mineral supplements. Optimum growth rate for the new isolate was observed at 64°C and pH 8.3. In this work, it was shown that wastewater from a wastewater treatment facility can be used as a low-cost alternative medium to cultivate M. wolfeii BSEL. Continuous gas fermentation fed with a synthetic biogas mimic along with H2 in a bubble column bioreactor using M. wolfeii BSEL as biocatalyst resulted in a CO2 conversion efficiency of 97% and a final methane (CH4) titer of 98.5%v, demonstrating the ability of the new strain for upgrading biogas to renewable natural gas.IMPORTANCEAs a methanogenic archaeon, Methanothermobacter wolfeii uses CO2 as electron acceptor, producing CH4 as final product. The metabolism of M. wolfeii can be harnessed to capture CO2 from industrial emissions, besides producing a drop-in renewable biofuel to substitute fossil natural gas. If used as biocatalyst in new-generation CO2 sequestration processes, M. wolfeii has the potential to accelerate the decarbonization of the energy generation sector, which is the biggest contributor of CO2 emissions worldwide. Nonetheless, the development of CO2 sequestration archaeal-based biotechnology is still limited by an uncertainty in the requirements to cultivate methanogenic archaea and the unknown longevity of archaeal cultures. In this study, we report the adaptation, isolation, and phenotypic characterization of a novel variant of M. wolfeii, which is capable of maximum growth with minimal nutrients input. Our findings demonstrate the potential of this variant for the production of renewable natural gas, paving the way for the development of more efficient and sustainable CO2 sequestration processes.
摘要：
在厌氧条件下使用富集培养从厌氧消化器中分离出一种新的甲烷热杆菌。通过16SrRNA基因测序对新分离物进行了分类学鉴定，并标记为M.wolfeiBSEL。对新变体的整个基因组进行测序并从头组装。发现了BSEL菌株和类型菌株之间的基因组变异，表明BSEL菌株的进化适应，在低浓度营养素下生长时具有优势。M.wolfeiiBSEL使用二氧化碳（CO2）作为独特的碳源和氢气（H2）作为电子供体，表现出wolfeii物种有史以来最高的比生长速率（0.27±0.03h-1）。M.wolfeiBSEL在以铵（NH4）为唯一氮源的环境中以此速率生长。培养BSEL菌株所需的矿物质含量相对较低，类似于没有矿物质补充剂的自来水的离子背景。在64°C和pH8.3下观察到新分离物的最佳生长速率。在这项工作中,研究表明，来自废水处理设施的废水可以用作低成本的替代培养基来培养M.wolfeiiBSEL。在使用M.wolfeiiBSEL作为生物催化剂的鼓泡塔生物反应器中，用合成沼气模拟物和H2进行连续气体发酵，导致CO2转化效率为97％，最终甲烷（CH4）滴度为98.5％v，证明了新菌株将沼气升级为可再生天然气的能力。重要的产甲烷古细菌，沃尔菲甲烷热杆菌使用二氧化碳作为电子受体，生产CH4作为最终产品。可以利用M.wolfeii的代谢来从工业排放中捕获二氧化碳，除了生产可再生生物燃料来替代化石天然气。如果用作新一代二氧化碳封存过程中的生物催化剂，M.wolfeii有潜力加速能源发电部门的脱碳，它是全球二氧化碳排放的最大贡献者。尽管如此，基于二氧化碳封存古细菌的生物技术的发展仍然受到培养产甲烷古细菌的要求的不确定性和古细菌培养物的未知寿命的限制。在这项研究中,我们报告了适应情况，隔离,和新的M.wolfeii变体的表型表征，能够以最少的营养输入实现最大的生长。我们的研究结果证明了这种变体用于生产可再生天然气的潜力，为开发更有效和可持续的二氧化碳封存过程铺平了道路。
