Calvo Diana C, Ontiveros-Valencia Aura, Krajmalnik-Brown Rosa, Torres Cesar I, Rittmann Bruce E
Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona, USA.
School of Sustainable Engineering and the Built Environment, Ira A. Fulton Schools of Engineering, Design Annex, Tempe, Arizona, USA.
Biotechnol Bioeng. 2021 Jun;118(6):2338-2347. doi: 10.1002/bit.27745. Epub 2021 Mar 30.
Microbiological conversion of CO into biofuels and/or organic industrial feedstock is an excellent carbon-cycling strategy. Here, autotrophic anaerobic bacteria in the membrane biofilm reactor (MBfR) transferred electrons from hydrogen gas (H ) to inorganic carbon (IC) and produced organic acids and alcohols. We systematically varied the H -delivery, the IC concentration, and the hydraulic retention time in the MBfR. The relative availability of H versus IC was the determining factor for enabling microbial chain elongation (MCE). When the H :IC mole ratio was high (>2.0 mol H /mol C), MCE was an important process, generating medium-chain carboxylates up to octanoate (C8, 9.1 ± 1.3 mM C and 28.1 ± 4.1 mmol C m d ). Conversely, products with two carbons were the only ones present when the H :IC ratio was low (<2.0 mol H /mol C), so that H was the limiting factor. The biofilm microbial community was enriched in phylotypes most similar to the well-known acetogen Acetobacterium for all conditions tested, but phylotypes closely related with families capable of MCE (e.g., Bacteroidales, Rhodocyclaceae, Alcaligenaceae, Thermoanaerobacteriales, and Erysipelotrichaceae) became important when the H :IC ratio was high. Thus, proper management of IC availability and H supply allowed control over community structure and function, reflected by the chain length of the carboxylates and alcohols produced in the MBfR.
将一氧化碳微生物转化为生物燃料和/或有机工业原料是一种出色的碳循环策略。在此，膜生物膜反应器（MBfR）中的自养厌氧细菌将电子从氢气（H₂）转移至无机碳（IC），并产生有机酸和醇类。我们系统地改变了MBfR中的氢气供应、无机碳浓度和水力停留时间。氢气与无机碳的相对可利用性是实现微生物链延长（MCE）的决定性因素。当H₂:IC摩尔比高（>2.0 mol H₂/mol C）时，MCE是一个重要过程，可生成高达辛酸（C₈，9.1±1.3 mM C和28.1±4.1 mmol C m⁻² d⁻¹）的中链羧酸盐。相反，当H₂:IC比低（<2.0 mol H₂/mol C）时，仅存在含两个碳的产物，因此氢气是限制因素。在所有测试条件下，生物膜微生物群落中与著名产乙酸菌醋杆菌最相似的系统发育型均得到富集，但当H₂:IC比高时，与能够进行MCE的科（如拟杆菌目、红环菌科、产碱菌科、热厌氧杆菌目和丹毒丝菌科）密切相关的系统发育型变得重要。因此，对无机碳可利用性和氢气供应进行适当管理，可以控制群落结构和功能，这体现在MBfR中产生的羧酸盐和醇类的链长上。
