Turning Wastes into Resources: Exploiting Microbial Potential for the Conversion of Food Wastes into Polyhydroxyalkanoates

Polyhydroxyalkanoates (PHA) are microbial polyesters produced by a wide range of microorganisms as storage materials. Besides displaying material properties similar to those of petroleum-based plastics, their intrinsic biodegradability makes them “green” candidates for solving plastic pollution issues. The PHA diversity, determined by monomer size as well as by polymer structure, translates into a wide range of material properties finding applications in different sectors. This tunability is due to the complex metabolic network that drives PHA biosynthesis in vivo, which makes every microorganism unique in its producing abilities. Despite such potentialities, the production of PHAs at large scale is hindered by the high cost of carbon substrate necessary to feed PHA producing microbes. In this regard, the use of food wastes as starting feedstock for microbial fermentation would represent a cost-effective way to boost PHA exploitation. This chapter examines the state of the art of food wastes conversion into PHAs, focusing on the strategies applied to develop microbial strains for producing PHAs with tailored properties and high yield. Examples of PHA production based on natural or engineered strains will be examined, and prospects and challenges for the effective exploitation of the processes will be presented.