Wastes valorization to polyhydroxyalkanoate: Key concepts and strategies to overcome potential challenges

Polyhydroxyalkanoates are promising substitutes for fossil fuel-based plastics, primarily distinguished by their biodegradability and biocompatible nature. Despite this fact, a major bottleneck that limits PHA availability in the marketplace is its exceptionally high production cost compared to conventional plastic and other biobased polymers. The waste-to-bioplastic concept may play a dual significant role in the utilization of waste material to develop a sustainable economy. Herein, the current review provides an in-depth analysis on the cost-effective synthesis of PHA from various waste streams such as food wastes, lipid wastes, pulp and paper wastes, agricultural wastes, as well as other organic wastes. Besides, the review reflected on the recent advancements in bacterial PHA synthesis, such as bioprocess optimization, metabolic pathways engineering, promotor engineering, CRISPR-Cas9 technology, cell morphology engineering, and synthetic biology approaches for effective PHA production. The review further suggested that the selection of suitable microbes, nature of feedstock, optimized bioprocess, and implementation of innovative metabolic engineering strategies would play a significant role in overcoming the potential barriers associated with PHA industrialization.