Isolation and Purification of Bacterially Produced Polyhydroxyalkanoates: Mechanisms, Limitations, and Current Advances

Polyhydroxyalkanoates (PHAs) are microbial polyesters that belong to a group of bioplastics with the potential to replace petroleum-derived plastics. Their main drawback is the high production cost, which puts them at a disadvantage compared to conventional plastics. A significant part of these costs arises from the isolation of PHAs from the cellular biomass of producing microorganisms. This review summarizes the main approaches used to recover both scl- and mcl-PHAs from native or dried (lyophilized) biomass, with attention to physical, chemical, and biological methods. Key parameters influencing extraction efficiency, polymer purity, and the final material properties are discussed, including pretreatment steps that often determine the overall outcome. The review also compares traditional halogenated solvent extraction with more environmentally acceptable alternatives and considers how different strategies can be combined to improve recovery. The current literature highlights the need for sustainable and economically acceptable processes that would make large-scale PHA production more feasible.