In silico analyses suggested that AbPhbC1 and AbPhbC2 are structurally functional, except that AbPhbC2 might require the PhaR subunit for its activity; this strongly suggests that it could be a class IV poly-β-hydroxyalcanoate synthase. UV-Vis scanning and NMR spectroscopy revealed the synthesis of poly-β-hydroxybutyrate by the A. baldaniorum enzyme AbPhbC1, indicating that the enzyme is functional.