Deletion of the pflA gene in Escherichia coli LS5218 and its effects on the production of polyhydroxyalkanoates using beechwood xylan as a feedstock.

Engineering of microorganisms to directly utilize plant biomass as a feedstock for the biosynthesis of value-added products such as bioplastics is the aim of consolidated bioprocessing. In previous research we successfully engineered E. coli LS5218 to produce polyhydroxyalkanoates (PHAs) from xylan. In this study we report further genetic modifications to Escherichia coli LS5218 in order to increase the lactic acid (LA) fraction in poly(lactic acid-co-3-hydroxyalkanoate) P(LA-co-HA) copolymers. Deletion of the pflA gene resulted in increased content of LA repeating units in the copolymers by over 3-fold compared with the wild type; however, this increase was offset by reduced yields in cell mass. Additionally, when acetate was used as a feedstock LA monomer incorporation reached 18.5 (mol%), which suggests that acetate can be used as a feedstock for the production of P(LA-co-HA) copolymers by E. coli.