Biodegradation of polyhydroxyalkanoates (PHAs): current state and future prospects

Ani Paloyan ¹ Mane Tadevosyan ^2,3 Diana Ghevondyan ^2,3 Lev Khoyetsyan ¹ Mariam Karapetyan ¹ Armine Margaryan ^2,3 Garabed Antranikian ⁴ Hovik Panosyan ^2,3*

• ¹ Scientific and Production Center 'Armbiotechnology', Armenian National Academy of Sciences, Yerevan, Armenia
• ² Yerevan State University, Yerevan, Armenia
• ³ Faculty of Biology, Yerevan State University, Yerevan, Armenia
• ⁴ Institute of Technical Biocatalysis, Hamburg University of Technology, Hamburg, Hamburg, Germany

Polyhydroxyalkanoates (PHAs) are biobased and biodegradable polymers that offer a sustainable alternative to conventional plastics, addressing the escalating concerns over plastic pollution. While their environmental advantages are well-documented, the efficient degradation of PHAs in natural and engineered environments remains a critical component of their lifecycle.This review provides a comprehensive overview of PHA-degrading bacteria isolated from diverse ecosystems and highlights the pivotal role of PHA depolymerases, which are essential for in achieving PHA circularity. Microbial adaptation to diverse environmental conditions, such as extreme temperatures, salinity, and pH, significantly influences the properties of their enzymes properties, including the stability, activity, and substrate specificity of PHA-degrading enzymes. These adaptations often enhance enzyme stability, activity, and substrate specificity, performance, enabling their functionality under challenging conditions.Consequently, extremophilic microorganisms are invaluable resources for discovering and engineering robust PHA depolymerases for industrial and environmental applications. This review underscores the urgent need for further research to improve the ecological and economic sustainability of PHA waste management.