초록
<P><B>Abstract</B></P> <P>Many heterologous transformation studies have been carried out using the <I>Cupriavidus necator</I> PHB<SUP>−4</SUP> strain to investigate the expression characteristics of various polyhydroxyalkanoate (PHA) synthase enzymes. In this study, we generated a recombinant <I>C. necator</I> PHB<SUP>−4</SUP> strain by transforming a plasmid (pMRC03) harbouring the synthetic <I>phaC2</I> gene of <I>Pseudomonas putida</I> CA-3. Under conditions favourable for expression of the <I>phaC2 <SUB>P.put</SUB> </I> <SUB>CA-3</SUB> gene, canola oil was used as carbon source for the synthesis of PHAs. The expressed synthase polymerised monomers of 3-hydroxybutyrate (3-HB), 3-hydroxyvalerate (3-HV) and 3-hydroxyhexanoate (3-HHx) in the recombinant <I>C. necator</I> PHB<SUP>−4</SUP> (pMRC03) strain. We then co-expressed the <I>phaC2<SUB>P.put</SUB> </I> <SUB>CA-3</SUB> gene with the native <I>phaC1<SUB>C.ne</SUB> </I> gene in wild type <I>Cupriavidus necator</I> H16 (<I>C. necator</I> H16 (pMRC03)). This co-expression produced a PHA blend of 3-HB, 3-HV, 3-HHx and 3-hydroxyoctanoate (3-HO) monomers in the presence of canola oil. Gas chromatography analysis revealed the presence of 94mol% 3-HB, 1mol% 3-HV, 4mol% 3-HHx and 1mol% 3-HO in a tetra-polymer. Thus, we confirmed that a synthetic <I>phaC2</I> gene encoding the synthase enzyme is functionally active with substrates ranging from short to medium chain length PHAs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The functional activity of PhaC2 synthase of <I>Pseudomonas putida</I> CA-3 is first reported. </LI> <LI> Heterologous expression is performed in <I>Cupriavidus necator</I> strains. </LI> <LI> PhaC2 synthase enzyme has a broad-substrate specificity of scl-PHA to mcl-PHA monomers. </LI> <LI> Co-expression study produced a PHA blend-polymer. </LI> <LI> Use of canola oil for scl-mcl PHA production is promising. </LI> </UL> </P>