Lignocellulosic feedstock: A review of a sustainable platform for cleaner production of nature’s plastics

The utilization of lignocellulosic feedstocks is the most promising, sustainable, and eco-friendly approach towards the production of polyhydroxyalkanoate since it entirely avoids the consumption of food crops. The use of these renewable and inexpensive feedstocks can make the production of polyhydroxyalkanoates affordable and facilitate the competitive commercialization of these carbon-neutral bio-based polyesters and their copolymers. Nevertheless, lignocellulosic biomass currently needs pretreatment to realize high sugar yields for the microbes to synthesize the polyhydroxyalkanoates. Steam pretreatment with dilute acids, followed by cellulase enzyme pretreatment, is a relatively practical approach to decompose these rigid biomasses into sugar monomers. However, the cost of commercial cellulase preparations continues to obstruct the large-scale economic conversion of lignocellulosic materials. Development of an eco-friendly consolidated bioprocessing system employing thermophiles for the single-step conversion of lignocellulose to polyhydroxyalkanoate, which excludes pretreatment and enzyme addition steps, and could be operative at low capital investment, would be an important breakthrough for the bioplastic industry. The scope of the present review is to highlight the significant and valuable research and development activities made in recent years to biosynthesize polyhydroxyalkanoates utilizing low-cost lignocellulosic biomass as the potential raw material. The future opportunity for the economical production of polyhydroxyalkanoate through unprocessed lignocellulosic biomass using thermophiles is also discussed.