Cloning and characterization of an unusual polyhydroxyalkanoate acid synthase (PHAC) gene from a chromobacterium Sp. isolated locally

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dc.contributor.authorKam, Yew Chee
dc.date.accessioned2014-10-27T04:12:35Z
dc.date.available2014-10-27T04:12:35Z
dc.date.issued2009
dc.descriptionMasteren_US
dc.description.abstractChromobacterium sp. is a bacterium capable of producing polyhydroxyalkanoates (PHA). The Chromobacterium sp. PHA synthase (PhaC) is able to polymerize shortchain- length PHA monomers, such as 3-hydroxybutyrate and 3-hydroxyvalerate. This bacterium is very interesting due to its ability to also produce a purple pigment, violacein. Production of violacein makes its colony purple in color, a color very unique among bacteria. Recently, this unique bacterium was successfully isolated from the famous ‘Air Terjun Telaga Tujuh’ in Langkawi, Malaysia. 16S rRNA analysis confirmed the identity of the isolate up to the genus level. In this study, the PHA synthase (phaC) gene was successfully cloned by using the PCR amplication technique. The Chromobacterium sp. phaC coding region consisted of 1704 bp, which encodes for a putative 568 amino acid protein. Results show that the PhaC of this bacterium has an unusual specificity towards 3-hydroxyvaleryl-CoA. This enzyme specificity was further supported by the ability of this isolate to synthesize poly(3-hydroxyvalerate) of 100 mol% purity from suitable substrates. When the cloned phaC was expressed in the PHA-negative mutant of Cupriavidus necator PHB–4, 64 wt% poly(3-hydroxybutyrate) of the dry cell weight was accumulated with fructose as the carbon source. In addition, when suitable 3-hydroxyvalerate (3HV) precursor carbon sources were used, PHA copolymers containing high molar fractions of 3HV monomers were synthesized. Most striking is the ability of the recombinant C. necator PHB–4 containing the Chromobacterium sp. phaC to accumulate poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) when crude palm kernel oil was used as the sole carbon source. This study demonstrates that the PhaC of Chromobacterium sp. has a broad substrate specificity similar to that of Aeromonas caviae.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/157
dc.language.isoenen_US
dc.subjectBiological Scienceen_US
dc.subjectCloningen_US
dc.subjectPolyhydroxyalkanoate acid synthaseen_US
dc.subjectChromobacterium sp.en_US
dc.titleCloning and characterization of an unusual polyhydroxyalkanoate acid synthase (PHAC) gene from a chromobacterium Sp. isolated locallyen_US
dc.typeThesisen_US
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