Metabolic engineering of Halomonas bluephagenesis for the production of ethylene glycol and glycolate from xylose

Halophilic Halomonas bluephagenesis, a natural producer of poly-3-hydroxybutyrate (PHB), was metabolically engineered to synthesize ethylene glycol and glycolate from xylose. Xylose utilization was achieved by overexpressing either the xylonate pathway or the ribulose-1-phosphate pathway. The key genes encoding for xylonate dehydratase and 2-keto-3-deoxy-xylonate aldolase in the xylonate pathway were screened. With further overexpressing aldehyde reductase gene yjgB, ethylene glycol accumulation was improved to 0.91 g/L, accompanied with 1.48 g/L of PHB accumulation. The disruption of native glycolate oxidase was found to be essential for glycolate production, and the defective recombinant strain produced 0.80 g/L glycolate with 1.14 g/L PHB in shake flask cultures. These results indicated that H. bluephagenesis has the potential to produce diverse metabolic chemicals from xylose.