Hydrogen Gas Boosts Microbial Production of Sustainable Chemicals
- Authors
- Pranav Sasidharan Nair, Hyunjin Kim, Seongcheol Kang, Byoung Seung Jeon, Largus T Angenent, Byoung-In Sang
- Journal
- Bioresource Technology
- Year
- 2026
- DOI
- 10.1016/j.biortech.2026.135089
- Study Type
- Cell Culture
- Outcome
- Positive
- Peer Reviewed
- Yes
- Country
- South Korea
- Health Condition
- Not applicable — biotechnology study
- Body System
- Microbial Metabolic Systems
TL;DR
Hydrogen supplementation improved microbial n-caproate production from glucose by increasing redox availability and favoring reverse β-oxidation.
Key Finding
__no_content__
Summary
This fermentation study tested hydrogen as an external reducing agent for n-caproate production by Caproiciproducens galactitolivorans. At 600 kPa hydrogen, n-caproate reached 8.0 g/L, with higher product selectivity and a large increase in intracellular redox-cofactor ratio. Multi-omics results suggested that hydrogen promoted reverse β-oxidation and redox-associated metabolism rather than fatty acid biosynthesis. Overall, the study supports hydrogen supplementation as a way to improve selective microbial production of medium-chain carboxylic acids.
Abstract
Medium-chain carboxylic acids, such as n-caproate, are attractive sustainable platform chemicals. However, their microbial production is often limited by electron availability and low product selectivity. This study investigated the effect of hydrogen supplementation on glucose-based n-caproate production by Caproiciproducens galactitolivorans. Batch fermentation was performed under various hydrogen pressures (0 to 600 kPa). At 600 kPa hydrogen,n-caproate reached 8.0 g L-1, accompanied by a 66% increase in n-caproate selectivity and a tenfold increase in the intracellular redox-cofactor ratio, consistent with enhanced redox-cofactor turnover. Multi-omics analysis indicated metabolic remodeling under hydrogen-enriched conditions, including the increased abundance of key enzymes in the reverse β-oxidation pathway and redox-associated functions. In contrast, although fatty acid biosynthesis genes were transcriptionally induced, this transcriptional increase was not reflected at the protein level, suggesting a metabolic response more consistent with reverse β-oxidation-supported n-caproate synthesis than with fatty acid biosynthesis. These results support the use of hydrogen as a clean external reducing agent for improving n-caproate yield and redox efficiency in defined microbial systems. This study provides mechanistic insights into redox-driven metabolic control and selective n-caproate production in a defined microbial chain elongation system.