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Careful CO Addition Enhances Autotrophic d-Lactate Formation With Engineered Acetobacterium woodii
Anna Stock1, Inka Sotzeck1, Kira Baur2
1Chair of Biochemical Engineering Technical University of Munich Garching Germany.
Engineering in Life Sciences
|February 19, 2026
Summary
Carbon monoxide (CO) addition to acetogen A. woodii gas fermentation impacts growth and d-lactate production non-linearly. Optimal CO levels enhance biomass and d-lactate yields, but high concentrations are inhibitory.
Area of Science:
- * Metabolic engineering and synthetic biology
- * Microbial biotechnology and bioprocess engineering
Background:
- * Acetogenic bacteria like A. woodii convert CO2 and H2 to acetate.
- * Metabolic engineering allows autotrophic production of non-native compounds, such as d-lactate.
- * Carbon monoxide (CO) can enhance reducing equivalents for biomass formation but also inhibits acetogen growth.
Purpose of the Study:
- * Investigate the impact of varying CO concentrations (0.6%-6.0%) on the autotrophic growth and d-lactate production of engineered A. woodii.
- * Determine the optimal CO partial pressure for maximizing biomass and d-lactate yields in batch fermentation.
- * Assess the inhibitory effects of CO on A. woodii.
Main Methods:
- * Batch fermentation of engineered A. woodii in stirred tank bioreactors with continuous gassing.
- * Controlled addition of CO (0.6%-6.0%) to the syngas mixture.
- * Monitoring of cell growth (biomass concentration) and d-lactate production.
Main Results:
- * No growth or product formation observed at 6.0% CO.
- * Biomass concentration significantly increased with 3.0% CO (89% improvement).
- * Highest d-lactate accumulation (6.2 g L-1, 189% improvement) achieved with 0.8% CO after a prolonged lag phase.
- * Growth and product formation showed non-linear dependence on CO concentration.
Conclusions:
- * A. woodii exhibits CO sensitivity, requiring precise control of CO levels in syngas.
- * Optimizing CO concentration is crucial for maximizing autotrophic biomass and d-lactate production.
- * Non-linear responses highlight the complexity of CO metabolism in engineered acetogens.
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