Wang, ZeyuChen, JuVeiga, María CarmenKennes, Christian2026-01-192026-01-192024-09-10WANG, Z., CHEN, J., VEIGA, M.C. y KENNES, C., 2024. Bioconversion of pure CO2 to caproic acid with zero valent iron: Optimizing carbon flux distribution in co-cultures of Acetobacterium woodii and Megasphaera hexanoica. Bioresource Technology, vol. 413, pp. 131480. ISSN 0960-8524. DOI 10.1016/j.biortech.2024.131480.0960-85241873-2976https://hdl.handle.net/2183/46936Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Acetobacterium woodii and Megasphaera hexanoica were co-cultured for caproic acid (CA) production from lactic acid (LA) and CO2. Also, various concentrations (1 g/L, 3 g/L, 5 g/L, and 10 g/L) of Zero Valent Iron (ZVI) were supplied to study its impact on the co-culture system. In flask experiments, 10 g/L LA and 1.0 bar CO2 produced 0.6 g/L CA with some biomass growth. ZVI increased LA consumption and CA production. Indeed, 3 g/L ZVI boosted CA production by 186 % and biomass accumulation by 103 %, suggesting that ZVI controls the carbon flux. Subsequent automated bioreactor studies showed that 3 g/L ZVI produced 1.842 g/L CA at stable pH, compared to 0.969 g/L without ZVI (control). Further, metabolic activity showed that both bacteria could directly use H2, generated by ZVI (3 g/L), as electron donor. Higher ZVI concentrations (10 g/L) resulted in Fe2+ causing excessive oxidation pressure on M. hexanoica, with its carbon flux flowing preferentially towards biomass. Enzyme assays confirmed that A. woodii preferred 10 g/L ZVI while M. hexanoica preferred 3 g/L for optimal bioconversion.eng© 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/bync- nd/4.0/ ).Attribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/Acetobacterium woodiiMegasphaera hexanoicaChain elongationGreenhouse gasCaproic acidZero valent ironjournal articleopen access10.1016/j.biortech.2024.131480