BACKGROUNDPoly(3-hydroxybutyrate) (PHB), which is completely biodegradable, is considered a potential candidate to replace a number of petroleum-derived polymers due to similar mechanical properties. In a previous study, inactivation of ndh gene in E. coli, which encodes the NDH-II dehydrogenase, resulted in significantly increased PHB production from either glucose or xylose as substrate. RESULTSIn this study, the xylose isomerase (EC:5.3.1.5), xylulokinase (EC:2.7.1.17) and the arabinose/xylose transport protein from Bacillus subtilis 168 (encoded by xylA, xylB and araE, respectively) were co-expressed in the ndh knockout strain, E. coliLJ03(pBHR68), which harbors the PHB biosynthesis genes from Ralstonia eutropha. The resulting strain E. coliLJ03(pBHR68+pM-ABE) was able to simultaneously utilize glucose and xylose to accumulate PHB. In flask cultivation, 3.67gL(-1) PHB was produced from a glucose-xylose mixture (10gL(-1) glucose and 5gL(-1) xylose), which was 2.09-fold higher than the production of the control strain E. coliJM109(pBHR68+pM-ABE). Ultimately, PHB production in fed-batch fermentation reached a maximum titer of 21.0gL(-1), representing a 1.93-fold increase relative to the control strain. CONCLUSIONResults indicated that the engineered E. coliLJ03 strain is significantly more efficient than the parent strain E. coliJM109 in producing PHB from mixed glucose-xylose feedstock. To the best of our knowledge, this is the first study describing the implementation of an exogenous xylose utilization pathway in E. coli for the production of PHB from mixed glucose-xylose feedstock-a model of lignocellulosic hydrolysate. (c) 2017 Society of Chemical Industry