Harnessing the potential of Cupriavidus necator for CO 2 capture from alcoholic fermentation and its bioconversion into poly(3-hydroxybutyrate).

The fermentation process in alcoholic beverage production converts sugars into ethanol and CO ₂ , releasing significant amounts of greenhouse gases. Here, Cupriavidus necator DSM 545 was grown autotrophically using gas derived from alcoholic fermentation, using a fed-batch bottle system. Nutrient starvation was applied to induce intracellular accumulation of poly(3-hydroxybutyrate) (PHB), a bioplastic polymer, for bioconversion of CO ₂ -rich waste gas into PHB. Grape marc, another by-product of wine production, was evaluated as a low-cost carbon source for the heterotrophic growth of C. necator, which was subsequently used as an inoculum for autotrophic cultures. The effect of agitation, CO ₂ headspace composition, and nitrogen concentration was tested, obtaining a maximum PHB concentration of 0.69 g/L, with an average CO ₂ uptake rate of 1.14 ± 0.41 mmol CO ₂ L ^-1 h ^-1 and 65 % efficiency of CO ₂ consumption. These findings lay the groundwork for developing carbon mitigation strategies in alcoholic fermentation processes coupled with sustainable biopolymer production.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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