Polyhydroxyalkanoate synthesis ability of the salt-tolerant bacterial strain Salinicola lusitanus BTNC26 isolated from the coastal zone in Vietnam and its application in food packaging film production.

Abstract

Recently, polyhydroxyalkanoates (PHAs) have attracted increasing attention as biodegradable alternatives to conventional petroleum-based plastics. This study aimed to identify bacterial strains synthesizing poly(3-hydroxybutyrate) (PHB) from coastal areas of Vietnam. Strain BTNC26, isolated as a PHA producer, was identified as Salinicola lusitanus BTNC26 via 16S rRNA gene sequencing (GenBank: PZ087081). Optimization of carbon (glucose) and nitrogen (yeast extract) sources, pH (7), temperature (30 °C), and NaCl (5%) enhanced cell growth and PHA accumulation. Under these conditions, biopolymer yield reached 73.07% after 96 h. FTIR, GC-MS, and NMR analyses confirmed that the extracted polymer was PHB: FTIR showed a carbonyl peak at 1710.52 cm⁻¹; ¹H/¹³C NMR revealed resonances at 169.14 (C = O), 67.62 (-CH-), 40.80 (-CH₂-), and 19.76 ppm (-CH₃); GC-MS displayed the 3-hydroxybutyric acid methyl ester molecular ion. Scale-up fermentation (200 mL to 100 L) with 10 g/L glucose supplementation yielded PHB concentrations of 4.76, 4.23, 3.98, and 3.59 g/L at 200 mL, 1 L, 5 L, and 100 L, respectively. Composite films prepared from extracted PHB blended with PBAT, CaCO₃, PEG, and glycerol formed thin, strong, and flexible films. Their biodegradability was confirmed by laboratory seawater degradation assays. These findings highlight the potential of the halophilic bacterium S. lusitanus for PHB production and biodegradable plastic applications in marine environments, and provide a basis for further scale-up and industrial development.