1 research outputs found
Target the Enhancement of DIET-Based CO<sub>2</sub>‑Dependent Methanogenesis via Synergy of Magnetite Addition and Inorganic Carbon Recirculation
In anaerobic systems, CO2-dependent methanogens
as terminal
electron acceptors determine the feasibility of organic degradation.
In this study, targeting the enhancement of CO2-dependent
methanogenesis, a strategy coupling the addition of magnetite and
inorganic carbon recirculation was proposed. The results showed that
the strategy facilitated the enrichment of Methanosaeta and Methanosarcina to the greatest extent (abundance
of 42.9 and 38.8%, respectively), and metaproteomic analysis revealed
that their enzymes coding for CO2-dependent methanogenesis
were maximally expressed, compared with the single strategy. Combined
with electrochemical analysis, magnetite was speculated to trigger
direct interspecies electron transfer (DIET)-based syntrophy with
extracellular redox-active mediators (Cyt C and flavins) in anaerobic
sludge. The ability of Methanosaeta and Methanosarcina to accept electrons was significantly improved, as evidenced by
the upregulated electron transfer proteins, such as F420H2 dehydrogenase, coenzyme F420 hydrogenase,
and CoB-CoM heterodisulfide reductase. Meanwhile, Methanosaeta and Methanosarcina enhanced HCO3– takeup into cells via an ABC-type transport system
under the condition of inorganic carbon recirculation, thus thermodynamically
inducing electron consumption and inorganic carbon reduction. In summary,
the coupling strategy had a great synergistic effect on the enhancement
of DIET-based CO2-dependent methanogenesis and endowed
the up-flow anaerobic sludge bed reactor with superior methanogenic
performance for stable anaerobic wastewater treatment