Valorization of Lignocellulose by Producing Polyhydroxyalkanoates Under Circular Bioeconomy Premises: Facts and Challenges

In light of the current concerns about environmental issues caused by the excessive use of fossil resources, more emphasis has been paid to the transition to a sustainable and circular economy. Bioplastics as eco-friendly products originating from biomass wastes have gained much attention to solve the problem of plastic pollution. Among them, polyhydroxyalkanoates (PHAs) are microbial polyesters produced using various feedstocks—renewable or recycled waste materials—contributing to a more sustainable commercial plastic life cycle by being a part of a circular bioeconomy. However, the scale-up of the PHAs process cost-effectively and sustainably remains challenging for large-scale industrial applications. This perspective article provides a comprehensive overview of the current insights into lignocellulosic biomass's role in achieving a circular bioeconomy. Emerging greener biomass conversion technologies are discussed to characterize energy demand, cost, and sustainability within biorefineries PHAs production. In addition, recent advances in synthetic biology and fermentation processes for PHAs production are discussed. Technological challenges, i.e., bioreactor set-up, downstream operation, and inconsistent properties to improve the sustainable production of PHAs and to help transfer this technology to real-world application, are also addressed.