Strategies for recovery and purification of poly[(R)-3-hydroxyalkanoates] (PHA) biopolyesters from surrounding biomass

To provide competitive alternatives to classical plastics, production of poly[(R)-3-hydroxyalkanoate] (PHA) biopolyesters has to become more economical. Downstream processing for PHA recovery from biomass plays a vital role in the PHA manufacturing process with respect to cost performance, material quality, and eco-balance. Several factors impact the selection of the adequate PHA recovery method: the microbial production strain, type and composition of PHA, PHA load in biomass, required product purity, availability of chemicals for PHA recovery, and impact on physical properties of PHA. In this review, we compare classical and novel strategies for PHA recovery from microbial biomass. Approaches for reducing solvent and energy inputs, focusing on obtaining endotoxin-poor PHA for medical application, are presented, as well as recent developments in efficient disruption of PHA-rich biomass. In addition, particularities of extremophiles and genetically modified microorganisms with properties facilitating the release and separation of PHA granules are discussed.