Economic utilisation of abundant lignocellulosic biomass (a material that serves a structural and protective role in plants and is most found in a plant cell wall) as a renewable and sustainable feedstock for fuel and chemical production would represent a profound shift in industrial carbon utilisation. As an easy to find and low-cost material, these sustainable resources could substitute for and compete with petroleum-based products.
For exploitation, lignocellulosic biomass must be first broken down into constituent compounds, such as sugars, so as to be more easily converted in chemical and biological processes. Unfortunately, lignocellulose is heterogenous and recalcitrant, and so highly resistant to depolymerisation (or the process of converting a polymer – a substance consisting of very large molecules composed of many repeating subunits – into a monomer – a molecule that can react together with other monomer molecules to form a larger polymer chain [process called polymerisation] – or a mixture of monomers). Luckily, many microorganisms have evolved enzyme activities to decompose components of the lignocellulosic biomass.
Converting renewable and underused lignocellulosic biomass to chemicals, including fuel and polymer precursors, would be of great strategic importance for sustainability and advancements in energy and chemical-based industries. Apart from majorly displacing the use of fossil fuels, it has the potential to add great value to agricultural by-products, forestry residues, and municipal waste. Biorefinery is also actively pursued in areas beyond fuel and is working so that a wide range of useful materials (for chemicals, energy, food, healthcare, etc.) can be derived from biomass.
Biomass-utilising organisms, which are widely distributed in species today, possess numerous lignocellulolytic enzymes acting on the (hemi)cellulose backbone, hemicellulose substituents, or cellulose-shielding lignin. The majority of these enzymes are secreted, making them promising biocatalysts for biomass conversion.
Research in these enzymes and in the area of biomass conversion has been plentiful, especially in the last couple of years and it presents a possible sustainable candidate for the role of successor to petroleum, which has already been proved and generally known to be inevitable finite.
Sources: Biomass Converting Enzymes as Industrial Biocatalysts for Fuels and Chemicals: Recent Developments (Matt D. Sweeney, Feng Xu)