Enzymatic activity screening in marine bacteria exposed to oxo-polyethylene in artificial marine microcosms

Oxo-polyethylene (oxo-PE) is marketed as a biodegradable plastic, yet its environmental degradation remains poorly understood, particularly in marine contexts. This study aimed to screen for bacterial isolates with enzymatic potential relevant to oxo-PE breakdown using a simulated marine environment. Microbial communities were enriched in Winogradsky columns containing oxo-PE sheets, and isolates were screened for enzymes known to contribute to polymer breakdown. After 60 days of incubation, no significant weight loss was detected in oxo-PE sheets. Surface-level alterations, including cracks and roughness, were observed using field emission scanning electron microscopy. Biofilms formed on the polymer surface over time yielded numerous bacterial isolates, of which 25 exhibited one or more enzymatic activities associated with polymer degradation, including alkane monooxygenase, laccase, lipase, and manganese peroxidase. Among them, isolate D30065 (Priestia megaterium) demonstrated the most diverse enzyme profile, suggesting potential for oxidative enzyme activity relevant to polyethylene breakdown. However, further studies are needed to directly evaluate the ability of this isolate to degrade oxo-PE. These findings highlight early microbial responses to oxo-PE exposure and provide a foundation for future studies on biodegradable plastic-microbe interactions in marine systems.