Aims: Halophilic micro-organisms have received much interest because of their potential biotechnological applications, among which is the capability of some strains to synthesize polyhydroxyalkanoates (PHA). Halomonas sp. SK5, which was isolated from hypersaline microbial mats, accumulated intracellular granules of poly(3-hydroxybutyrate) [P(3HB)] in modified accumulation medium supplemented with 10% (w/v) salinity and 3% (w/v) glucose. Methods and Results: A cell density of approximately 3Á0 g l À1 was attained in this culture which yielded 48 wt% P(3HB). The bacterial strain was also capable of synthesizing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] when cofed with relevant precursors. Feeding with sodium valerate (0Á7 mol l À1 carbon) at various time intervals within 36 h resulted in 3HV molar fractions ranging from 6 up to 54 mol%. Oil palm trunk sap (OPTS) and seawater as the carbon source and culture medium respectively facilitated a significant accumulation of P(3HB). Simplified downstream processing based on osmotic lysis in the presence of alkali/detergent for both dry and wet biomass resulted in approximately 90-100% recovery of polymers with purity as high as 90%. Weight-average molecular weight (M w ) of the polymers recovered was in the range of 1-2 9 10 6 . Conclusions: Halomonas sp. SK5 was able to synthesize P(3HB) homopolymer as well as P(3HB-co-3HV) copolymer from various carbon sources. Significance and Impact of the Study: This is the first time a comprehensive study of both production and downstream processing is reported for Halomonas spp.

Aims: This study evaluates potentials of Cupriavidus necator PHB  4 transformant harboring the highly active polyhydroxyalkanoate synthase gene (phaC) of a locally isolated Chromobacterium sp. USM2 for its ability to incorporate 3-hydroxyheptanoate (3HHp) monomer. Methodology and results: A mixture of fructose and sodium heptanoate fed to the culture gave rise to poly(3hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyheptanoate), [P(3HB-co-3HV-co-3HHp)] terpolymer synthesis, with traces of 3HHp monomers confirmed through gas chromatography (GC), proton (1 H) and carbon (13 C) NMR spectra. Conclusion, significance and impact of study: This study has revealed that the PHA synthase of Chromobacterium sp. USM2 has a broad range of substrate specificity. The synthase is able to polymerize 3-hydroxyalkanoate monomers having 4-7 carbon atoms.