(A) study on poly(3-hydroxybutyrate) production from lignocellulosic biomass by Ralstonia eutropha

Abstract

Lignocellulosic raw materials are being extensively examined for the production of biofuel, biochemicals, and biopolymers. Xylose, which is one of the major components of hydrolyzed lignocelluloses, is a promising carbon source for microbial fermentation. In this study, recombinant R. eutropha NCIMB11599 expressing the E. coli xylA and xylB genes encoding xylose isomerase and xylulokinase respectively, named R. eutropha (pKM212-XylAB) was constructed and examined for the biosynthesis of poly(3-hydroxybutyric acid) (P(3HB)) from xy-lose. R. eutropha (pKM212-XylAB) was observed to utilize xylose as a sole carbon source. It accumulated 2.3 g/L of P(3HB) with a cellular P(3HB) content of 31.0 wt% form of 10 g/L of glucose and 10 g/L of xylose resulted in higher P(3HB) concentration and content of 5.7 g/L and 78.1 wt%, respectively. The P(3HB) concentration and con-tent further increased to 8.8 g/L and 88.7 wt% when a medium containing 15 g/L of glucose and 5 g/L of xylose was used. A hydrolysate solution of sunflower stalk as model lignocellulosic biomass was prepared and exam-ined for its application as feedstock in P(3HB) fermentation. The recombinant R. eutropha completely con-sumed glucose and xylose in the sunflower stalk-based medium to produce 7.8 g/L of P(3HB) with a P(3HB) content of 71.3 wt%.