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The fermentation of carbon dioxide (CO₂) with hydrogen (H₂) uses available low-cost gases to synthesis acetic acid. Here, we present a two-stage biological process that allows the gas to liquid transfer (Bio-GTL) of CO₂ into the biopolymer polyhydroxybutyrate (PHB). Using the same medium in both stages, first, acetic acid is produced (3.2 g L⁻¹) by Acetobacterium woodii from 5.2 L gas-mixture of CO₂:H₂ (15:85 v/v) under elevated pressure (≥2.0 bar) to increase H₂-solubility in water. Second, acetic acid is converted to PHB (3 g L⁻¹ acetate into 0.5 g L⁻¹ PHB) by Ralstonia eutropha H16. The efficiencies and space-time yields were evaluated, and our data show the conversion of CO₂ into PHB with a 33.3% microbial cell content (percentage of the ratio of PHB concentration to cell concentration) after 217 h. Collectively, our results provide a resourceful platform for future optimization and commercialization of a …