Biofuels derived from lignocellulose are attractive alternative fuels but their
production suffers from a costly and inefficient saccharification step that uses fungal
enzymes. One route to improve this efficiency is to better understand the transcriptional
regulation and responses of filamentous fungi to lignocellulose. Sensing and initial
contact of the fungus with lignocellulose is an important aspect. Differences and
similarities in the responses of fungi to different lignocellulosic substrates can partly be
explained with existing understanding of several key regulators and their mode of
action, as will be demonstrated for Trichoderma reesei, Neurospora crassa and
Aspergillus spp. The regulation of genes encoding Carbohydrate Active enZymes
(CAZymes) is influenced by the presence of carbohydrate monomers and short
oligosaccharides, as well as the external stimuli of pH and light. We explore several
important aspects of the response to lignocellulose that are not related to genes encoding
CAZymes, namely the regulation of transporters, accessory proteins and stress
responses. The regulation of gene expression is examined from the perspective of mixed
cultures and models that are presented for the nature of the transcriptional basis for any
beneficial effects of such mixed cultures. Various applications in biofuel technology are
based on manipulating transcriptional regulation and learning from fungal responses to
lignocelluloses. Here, we critically access the application of fungal transcriptional
responses to industrial saccharification reactions. As part of this chapter, selected
regulatory mechanisms are also explored in more detail.
Keywords: Accessory proteins, Aspergillus, biofuel, CAZyme, gene regulation,
inducer, light, lignocellulose, mixed culture, model, Neurospora, nucleosome, pH,
saccharification, signalling, stresses, transcription factor, transporter, Trichoderma,
XlnR/XYR1/XLR-1.
