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.