Title
Microbial and metabolic variations in pH-dependent chain elongation: Co-utilization of lactate and ethanol vs. lactate-based production
Authors
[ 1 ] Instytut Inżynierii Środowiska i Instalacji Budowlanych, Wydział Inżynierii Środowiska i Energetyki, Politechnika Poznańska | [ P ] employee
Scientific discipline (Law 2.0)
Year of publication
2025
Published in
Article type
scientific article
Publication language
english
Keywords
EN
- Caproiciproducens
- Chain elongation
- Solventogenesis
- Caproate
- Propionate
- Propanol
Abstract
EN There is growing interest in utilizing waste streams in mixed culture fermentation (MCF) for carboxylate chain elongation (CE). Lactate and ethanol are the most well-recognized electron donors (ED) in CE; however, previous attempts to co-utilize them have yielded varying results. The impact of ethanol as an additional ED for lactate-based CE on microbiome structure and metabolite production was investigated in continuously-fed bioreactors across a pH range of 5.5–7.0. Caproiciproducens spp. were recognized as the primary potential caproate producers at pH 5.5–6.5, supported by Clostridium sensu stricto 12 spp., Clostridia UCG-014 spp., and Oscillibacter spp. It was demonstrated that ethanol, as an additional ED at pH 6.0 and 6.5, increased caproate concentration by approximately 35% compared to lactate-based CE, while the combination of pH 5.5 and ethanol addition inhibited lactate-based CE and induced solventogenesis, despite the microbiome being enriched with potential chain elongators. The microbiome structure exhibited the greatest shifts at near-neutral pH affecting caproate production. Lactate-based CE was characterized by competition between chain elongators and unidentified microorganisms affiliated with the Oscillospiraceae and Lachnospiraceae families. On the other hand, the co-utilization of ethanol and lactate at neutral pH favoured the growth of Anaerotignum propionicum and Clostridium sensu stricto 7 spp. Although neutral pH favoured the growth of chain elongators' competitors, specific ASVs associated with Caproiciproducens spp. still appeared, leading to an increase in its relative abundance up to 19.8%. This study highlights how ethanol as a co-ED for lactate-based CE influenced metabolite profiles and microbial community structure across different pH ranges.
Date of online publication
25.06.2025
Pages (from - to)
165367-1 - 165367-11
Comments
Article Number: 165367
License type
CC BY (attribution alone)
Open Access Mode
czasopismo hybrydowe
Open Access Text Version
final published version
Date of Open Access to the publication
in press
Ministry points / journal
200
Impact Factor
13,2 [List 2024]
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