RT info:eu-repo/semantics/article T1 Use of a highly specialized biocatalyst to produce lactate or biohydrogen and butyrate from agro-industrial resources in a dual-phase dark fermentation A1 García Depraect, Octavio A1 León Becerril, Elizabeth K1 Hydrogen - Biotechnology K1 Hydrogen as fuel K1 Renewable energy resources K1 Energías renovables K1 Biotechnology K1 Biotecnología K1 Biorefinery K1 Dark fermentation K1 Organic acids K1 Organic wastes K1 Residuos orgánicos K1 2303.14 Hidrogeno K1 5312.05 Energía K1 2302.12 Fermentación K1 2301 Química Analítica AB This study aimed at investigating the feasibility of using a highly specialized bacterial inoculum harboring lactic acid bacteria (LAB) and lactate-oxidizing, hydrogen-producing bacteria (LO-HPB) to produce either lactate or biohydrogen and butyrate from several agro-industrial resources via dual-phase dark fermentation. The feedstocks were fruit–vegetable waste, cheese whey, coffee wastewater, tequila vinasse, and maize processing wastewater, and were tested in both mono- and co-fermentation. The results obtained indicated that the biocatalyst used was able to perform a dual-phase lactate fermentation, producing high lactate (13.1–36.4 g/L), biohydrogen (0.2–7.5 NL H2/Lfeedstock, equivalent to 0.3–1.7 mol H2/mol hexose), and butyrate (3.3–13.9 g/L) with all the tested feedstocks. A series of self-fermentation tests were also performed with crude cheese whey and fruit–vegetable waste for comparison purposes. Compared to inoculum-aided fermentations, the self-fermentation exhibited a reduced bioconversion efficiency. Short-length 16S rRNA gene sequencing analysis showed that LO-HPB was the dominant microbial group (86.0%) in the biocatalyst, followed by acetic acid bacteria (5.8%) and LAB (5.7%). As expected, the molecular analysis also showed significant differences in the microbial community structure of the biocatalyst and those that evolved from self-fermentation. Besides lactate fermentation and oxidation, the biocatalyst also assisted the bi-phasic lactate fermentation via oxygen consumption, and apparently, via substrate hydrolysis. Overall, this study can lay the foundation for robust inoculum development, which is of special significance in the field of dark fermentation, and proposes an innovative bioprocess for agro-industrial valorization through a trade-off approach, tailoring the metabolic pathway to the target product(s). PB MDPI SN 2311-5637 YR 2023 FD 2023 LK https://uvadoc.uva.es/handle/10324/66627 UL https://uvadoc.uva.es/handle/10324/66627 LA eng NO Fermentation, 2023, Vol. 9, Nº. 9, 787 NO Producción Científica DS UVaDOC RD 06-ago-2024