Polyhydroxyalkanoate (PHA) is a group of biopolymer that accumulates intracellularly as carbon and energy storage materials in numerous microorganisms, usually when grown under the limitation of a nutrient such as nitrogen, oxygen, phosphorus, sulfur, magnesium and in the presence of excess carbon. In this study, PHA accumulating bacteria were isolated from soil samples collected from mangroves in Giao Thuy district, Nam Dinh province. Twelve baterial strains were screened for PHA production with glucose as carbon source. The strain ND153 was chosen as a potential PHA producer. Strain ND153 is a slight halophilic, pH neutral, mesophilic, motile, Gram-positive, spore formation, and rod-shaped baterium. The bacterium is a heterotroph, able to utilize various nitrogen and carbon sources. PHA from strain NDl53 was purified and used for magnetic resonance spectroscopic analysis. Based on H-nuclear magnetic resonance (H-NMR) spectroscopic analysis, it was found that strain NDl53 produced a homopolymer of 3-hydroxybutyric acid (poly 3-hydroxybutyrate - PHB) - a typical polymer accumulated by many microorganisms in nature. In a medium with glucose as carbon source, the maximum PHB content of 82 percent of cell dry weight was obtained after 30h of cultivation in shake flask under MgSO4 limitation.
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