Hydraulic Retention Time and Electric Stimuli as Key Levers for Tailoring Mixotrophic Consortia Toward Enhanced Volatile Fatty Acid Production and Carbon Capture

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🔬研究者:This paper provides mechanistic insights into how hydraulic retention time and electric stimuli shape microbial communities and carbon flux in bioelectrochemical systems, offering a foundation for optimizing continuous CO2 conversion processes.

🏢実務担当者:The demonstrated use of HRT as a control lever for enhanced acetate production could inform the design of industrial-scale bioreactors for carbon capture and value-added chemical synthesis.

<title>Abstract</title> <p> Background Continuous bioelectrochemical systems represent a promising platform for converting CO ₂ into value-added bioproducts, yet operational strategies to enhance carbon capture and product selectivity remain limited. While mixotrophic electrofermentation improves process stability and performance, the role of hydraulic retention time (HRT) in shaping microbial community specialization and inorganic carbon utilization in continuous systems remains poorly understood. Results A continuous electrostimulated bioreactor was operated at a constant potential of 300 mV for approximately 1200 h under three HRTs (33, 19, and 14 h). Decreasing HRT promoted the enrichment of a specialized mixotrophic consortium, with <italic>Enterococcus</italic> and <italic>Clostridium</italic> dominating the planktonic phase and <italic>Desulfovibrio</italic> and <italic>Enterococcus</italic> enriched in the electrode biofilm. This syntrophic organization enhanced biomass-specific IC removal by 2.6-fold (from 4.92 to 12.88 mg g ^− 1 h ^− 1 ) and redirected carbon flux toward acetate, a key product of acetogenic pathways. Acetate reached 1470 mg L ^− 1 with a volumetric productivity of 107 mg L ^− 1 h ^− 1 at HRT = 14 h. Batch assays revealed that ~ 38% of the acetate exceeded heterotrophic stoichiometry, indicating additional CO ₂ /HCO ₃ ⁻ fixation. Functional predictions further revealed the enrichment of carbon fixation pathways, particularly in the electrode-associated biofilm, suggesting that electrode-associated taxa contributed to the generation of reducing equivalents and supported autotrophic metabolism. Conclusion Reducing HRT enhanced inorganic carbon utilization and selectively increased acetate production in a continuous electrostimulated bioreactor. This effect was associated with the enrichment of a functionally specialized microbial consortium and the activation of carbon fixation pathways, particularly in the electrode-associated biofilm, highlighting the role of spatial organization in driving carbon flux. These findings demonstrate that HRT can be used as a practical and energy-efficient engineering strategy to control microbial function and improve CO ₂ /HCO ₃ ⁻ valorization, advancing the development of selective and scalable electrobiotechnological processes. </p>

• Research Square https://doi.org/10.21203/rs.3.rs-9518331/v1first seen 2026-05-15 16:29:31 · last seen 2026-05-28 04:24:49
• openalex https://doi.org/10.21203/rs.3.rs-9518331/v1first seen 2026-05-17 06:46:52 · last seen 2026-06-13 05:00:12