Biodegradable plastics: A review of environmental degradation and microbial roles

Abstract

Biodegradable plastics are gaining traction as promising sustainable alternatives to conventional petroleumbased plastics. However, our understanding of biodegradation behavior in natural environments and the roles of specific microorganisms involved in the process remains limited. To address this, the current review examined seven types of biodegradable plastics commonly used in industry, focusing on their degradation behavior across different environmental media (soil, compost, and aquatic systems) and comparing their biodegradation rates under internationally certified standard conditions. The results revealed substantial variability in degradation behavior depending on both material type and environmental conditions. Among the plastics examined, polyhydroxyalkanoates (PHAs) exhibited the highest biodegradation rates across all tested conditions. Under composting conditions specified by the internationally recognized standard ISO 14855, polycaprolactone (PCL) showed degradation exceeding 90%, while polybutylene succinate exceeded 30%. At the microbial level, various enzymes including esterases, cutinases, lipases, and proteases are involved in polymer chain cleavage during biodegradation. In terms of microbial degradation, generalist degraders such as Bacillus, Pseudomonas, and Aspergillus were identified, alongside strains with plastic-specific activity. Notably, both bacteria and fungi were effective in degrading PHAs and PCL, whereas relatively low degradation rates were observed for polylactic acid and polybutylene adipate terephthalate. These findings underscore the need to identify novel microbial strains and strategies capable of enhancing biodegradation performance. Overall, this review provides essential data for assessing the environmental degradation and sustainability of biodegradable plastics and offers a scientific basis for future policy development and industrial applications.