Bioconversion of lignin and its derivatives into polyhydroxyalkanoates: Challenges and opportunities

Renewable energy resources are considered to be promising for the development of a sustainable circular economy. Among various alternatives, the microbial route for various biofuels production is quite lucrative. Use of cellulose and lignocellulose for methane, H2, organic acids, ethanol, and cellulase has been explored a lot in the past few decades. The major leftover or a coproduct of these processes belongs to lignin—an aromatic cross‐link polymer and one of the most abundant complex compounds on earth. A successful bioconversion route of lignin into high‐value products is highly desirable for biorefinery perspective. It requires a complex set of enzymes/catalysts to decompose lignin through depolymerization and oxygen removal leading to its monomers that can be metabolized by engineered organisms to synthesize muconic acids, polyhydroxyalkanoates (PHAs), methane, and other high‐value products. This article will focus on the opportunities and challenges in the bioconversion of lignin and its derivatives into PHAs.