title: Enhanced production of polyhydroxyalkanoates (PHAs) from beechwood xylan by recombinant Escherichia coli.
abstract: Microbial conversion of plant biomass to value-added products is an attractive option to address the impacts of petroleum dependency. In this study, a bacterial system was developed that can hydrolyze xylan and utilize xylan-derived xylose for growth and production of polyhydroxyalkanoates (PHAs). A β-xylosidase and an endoxylanase were engineered into a P(LA-co-3HB)-producing Escherichia coli strain to obtain a xylanolytic strain. Although PHA production yields using xylan as sole carbon source were minimal, when the xylan-based media was supplemented with a single sugar (xylose or arabinose) to permit the accumulation of xylan-derived xylose in the media, PHA production yields increased up to 18-fold when compared to xylan-based production, and increased by 37 % when compared to production from single sugar sources alone. ¹H-Nuclear magnetic resonance (NMR) analysis shows higher accumulation of xylan-derived xylose in the media when xylan was supplemented with arabinose to prevent xylose uptake by catabolite repression. ¹H-NMR, gel permeation chromatography, and differential scanning calorimetry analyses corroborate that the polymers maintain physical properties regardless of the carbon source. This study demonstrates that accumulation of biomass-derived sugars in the media prior to their uptake by microbes is an important aspect to enhance PHA production when using plant biomass as feedstock.
authors.affiliation: Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 318 Jahn Lab, 1 Forestry Dr, Syracuse, NY, 13210, USA.
authors.forename: Lucia
authors.initials: L
authors.lastname: Salamanca-Cardona
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Ashe
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Stipanovic
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Nomura
mesh_terms: D002151:Calorimetry; D002850:Chromatography, Gel; D003470:Culture Media / Q000737:chemistry; D043364:Endo-1,4-beta Xylanases / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D029964:Fagus / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D060847:Metabolic Engineering; D054813:Polyhydroxyalkanoates / Q000378:metabolism*; D014990:Xylans / Q000378:metabolism*; D014995:Xylosidases / Q000235:genetics / Q000378:metabolism
chemical_list: D003470:Culture Media; D054813:Polyhydroxyalkanoates; D014990:Xylans; D014995:Xylosidases; D043364:Endo-1,4-beta Xylanases