Chromobacterium sp. is a bacterium capable of producing polyhydroxyalkanoates (PHA). The Chromobacterium sp. PHA synthase (PhaC) is able to polymerize short -chain-length PHA monomers, such as 3-hydroxybutyrate and 3-hydroxyvalerate. This bacterium has been long recognized for its production of violacein, a violet non-diffusible pigment giving colonies a dark purple to black. Recently, this unique bacterium was successfully isolated from the famous ‘7 Wells’ in Langkawi, Malaysia. 16S rRNA analysis confirmed the identity of the isolate up to the genus level. Further biochemical tests are needed to fully confirm the specie of the strain.
In our laboratory, the PHA synthase (phaC) gene of Chromobacterium sp. was successfully cloned by using PCR amplification techniques. Preliminary studies suggested that the PhaC of this bacterium has an unusual specificity towards 3-hydroxyvaleryl-CoA. This enzyme specificity is further supported by the ability of this isolate to synthesize poly(3-hydroxyvalerate) of 100 mol% purity from suitable substrates. The aim of this study is to determine that the gene is functionally active when complemented with Ralstonia eutropha, PHB–4. This is due to the ability of R. eutropha to utilize a broad range of carbon sources. When the cloned fragment is complemented with a PHA-negative mutant of PHB–4, the result is the accumulation of 10.6 mol% poly-3-hydroxybutyrate of the dry cell weight when fructose was used as the carbon source. This result shows that the cloned PhaC is functionally active because R. eutropha PHB–4, which is depleted of its synthase gene, is able to produce P(3HB).
