ABSTRACT

Introduction When considering industrial scale processes for the conversion of lignocellulosic feedstocks for the production of fuels and chemicals, a number logistical and technical factors must be considered, including feedstock availability, cost, sustainability, transportation, front end processing, and conversion. These considerations can be thought of as the general susceptibility of chosen/available feedstocks to the intended conversion process. The concept of feedstock susceptibility, or recalcitrance, has often been the driving force underpinning the selection of key 2nd generation biomass conversion technologies. The recalcitrance of the feedstock towards current conversion processes involves a number of factors from simple challenges, such as chemical composition, substrate density, particle size, and the initial moisture content of the supplied feedstock; to extremely complex issues associated with the highly integrated nature of the structural carbohydrates that develop within plant cell walls. The latter topic has been studied with growing intensity in recent years and has become deeply invested in a diversity of disciplines, including process and reactor design, enzyme engineering, advanced microscopy, numerical modeling, and studies of the emergent properties of the plant cell wall.