title: A feeding strategy for incorporation of canola derived medium-chain-length monomers into the PHA produced by wild-type Cupriavidus necator.
abstract: The aim of this study was to increase the density of wild type Cupriavidus necator H16 biomass grown on fructose in order to produce sufficient copolymer of short-chain-length (scl) and medium-chain-length (mcl) polyhydroxyalkanoate (PHA) from canola oil for mechanical testing of the PHA. Initial batch cultivation on fructose was followed by exponential feeding of fructose at a predetermined μ to achieve 44.4 g biomass/l containing only 20 % w/w of polyhydroxybutyrate (PHB) with a Y(x/fructose) of 0.44 g/g. In a third stage, canola oil was added under N-limited conditions to produce 92 g/l of biomass with 48 % w/w scl-mcl PHA. Using known standards, the PHA composition was confirmed by GC-MS analysis as 99.81 % 3-hydroxybutyrate, 0.06 % 3-hydroxyvalerate, 0.09 % 3-hydroxyhexanoate and 0.04 % 3-hydroxyoctanoate. The melting temperature (179 °C), crystallinity (54 %), tensile stress (25.1 Mpa) and Young's modulus (698 Mpa) for a PHB standard decreased to 176 °C, 52 %, 19.1 and 443 Mpa respectively for C. necator PHA produced in the 3-stage process.
authors.affiliation: Chemical Engineering, Queen's University, Kingston, ON, K7L 3N6, Canada.
authors.forename: Arthi
authors.initials: A
authors.lastname: Rathinasabapathy
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Ramsay
authors.forename: Juliana A
authors.initials: JA
authors.lastname: Ramsay
authors.forename: Fermín
authors.initials: F
authors.lastname: Pérez-Guevara
mesh_terms: D018533:Biomass; D002849:Chromatography, Gas; D003470:Culture Media / Q000737:chemistry; D020118:Cupriavidus necator / Q000254:growth & development* / Q000378:metabolism*; D005229:Fatty Acids, Monounsaturated / Q000378:metabolism*; D005632:Fructose / Q000378:metabolism*; D013058:Mass Spectrometry; D054813:Polyhydroxyalkanoates / Q000737:chemistry / Q000378:metabolism*; D000074262:Rapeseed Oil; D044366:Transition Temperature
chemical_list: D003470:Culture Media; D005229:Fatty Acids, Monounsaturated; D054813:Polyhydroxyalkanoates; D000074262:Rapeseed Oil; D005632:Fructose