Polyhydroxyalkanoate production by engineered Halomonas grown in lignocellulose hydrolysate

Lignocellulose is the most abundant terrestrial biomass type, and lignocellulose hydrolysate has the potential to replace glucose for microbial fermentation. Halomonas bluephagenesis has significant advantages in producing bioplastics polyhydroxyalkanoates (PHA), but there is relatively little research on the use of lignocellulose hydrolysate for this strain. In present study, H. bluephagenesis was engineered to use xylose and lignocellulose hydrolysate to produce PHB. Firstly, four xylose metabolism pathways were established. Secondly, several xfp genes were compared and genes in pathway I (xylA and xfp gene) were integrated into the genome. Thirdly, H. bluephagenesis was found to be able to utilize glucose and xylose simultaneously. H. bluephagenesis T39 containing xylA and xfp generated 15 g/L CDW containing 76 wt% PHB when cultured in lignocellulose hydrolysate, and it was grown to 62 g/L CDW containing 67 wt% PHB in a 7 L bioreactor. H. bluephagenesis T43 harboring xylA was found able to synthesize P(3HB-4HB-3HV) containing 3-hydroxybutyrate (3HB), 4-hydroxybutyrte (4HB) and 3-hydroxyvalerate (3HV) when grown on lignocellulose hydrolysate.