Characterization and biodegradation of polyhydroxyalkanoates (PHAs) in a simulated marine environment

Polyhydroxyalkanoates (PHAs) are microbially produced biodegradable polyesters with adjustable properties, positioning them as promising candidates to replace conventional plastics, particularly in single-use applications. In this study, films of P(3HB) and its copolymers—P(3HB- co -2 mol% 3HHx), P(3HB- co -6 mol% 3HHx), and P(3HB- co -27 mol% 4HB)—were fabricated by solvent casting and examined for their material properties and degradation under simulated marine conditions. All PHA films exhibited signs of degradation beginning in the second week of experiment, while the polylactic acid (PLA) showed no visible change after one month. Gravimetric analysis revealed continuous mass loss of PHA films between weeks 2 and 4, whereas PLA maintained stable weight throughout the study. SEM imaging further demonstrated surface erosion of PHA films, consistent with the weight-loss data. From seawater and degraded film samples, 54 microbial strains capable of degrading P(3HB) were isolated, among which Alcanivorax venustensis FD9.1 produced the largest clear zone on P(3HB) agar plates, suggesting its potential for PHA-degrading enzyme production. Collectively, these findings validate the marine degradability of PHA films and identify microbial candidates relevant for advancing bioplastic degradation technologies, reinforcing the promise of PHAs as sustainable substitutes for single-use plastics in marine ecosystems.