Role of gene regulation in the action of lignocellulolytic enzymes

Abstract

Second-generation ethanol (2G), produced from plant biomass residues, such as rice straw and sugarcane bagasse, are promising alternatives towards increasing biofuel contribution in the world energy outlook. The efficient use of alternative carbon sources requires highly specific enzymatic complexes, mainly composed of cellulases and hemicellulases. The high cost of enzymatic hydrolysis, associated with a deficient production process, make 2G ethanol less competitive than traditional energy sources. Filamentous fungi stand out as organisms that produce lignocellulolytic enzymes. Moreover, they frequently appear in biotechnological research related to the genetic improvement of lineages, having the goal of increasing enzyme production. One way to increase enzymatic complexes production is by manipulation of gene expression of enzymes of interest, which can occur at the transcriptional level. Transcription factors (TF’s) are elements that act in the repression or activation of genes. Therefore, regulation of transcription factors, instead of a target gene, is an efficient and promising strategy to improve enzymatic cocktails produced by filamentous fungi. Overall, this work aims to provide a didactic revision on the action of transcription factors on top of the gene regulation of lignocellulolytic enzymes in fungi. The increment in gene expression and the optimization of enzyme production can turn enzymatic hydrolysis of plant biomass into a more accessible process, allowing an expansion of 2G ethanol contribution in the global market of biofuels.