Polyhydroxyalkanoates (PHAs) – Production, Properties, and Biodegradation

Pollution of aquatic and terrestrial environments due to fossil plastics, including microplastics, and release of excess greenhouse gases that are increasing the earth's temperature are now equivocally linked to fossil fuel use. Bioinspired solutions emulating nature's strategy of circularity of materials and greenhouse gases have been known to mankind for quite some time. Biopolymers with plastic-like properties, characterized by the attributes biobased, biosynthesized, biodegradable, and biocompatible, offer solutions to these problems. Polyhydroxyalkanoates (PHAs), a class of biopolyesters produced by microbes from renewable resources as secondary metabolites, are increasingly attracting attention because of their circularity due to their end-of-life attributes. They also possess plastic-like properties that are beneficial to humankind. This chapter collates major aspects of these biopolyesters, including next-generation raw materials for their production, types of PHAs that are industrially relevant with beneficial properties, the different groups of microbial PHA-producing strains, bioengineering concepts for more efficient PHA production, and new downstream processing approaches for sustainable and effective product recovery. Special focus is dedicated to biodegradability aspects and conceivable end-of-life options for spent PHAs, which are already the central topic in designing solutions for packaged items such as food and beverage. PHA material solutions are poised to grab more attention from policy makers, industry, and consumers as their industrial production increases, and their presence in the market highlights their renewable nature, functionality in use, and multiple end-of-life options.