Foreshadowing an exponential market: A brief story, applications, and perspectives of CRISPR/Cas system for the production of (hemi-)cellulases in filamentous fungi

The demand to develop protein production systems that are both economically and scientifically viable is reflected in the global scenario, where filamentous fungi, due to their interesting characteristics such as the high capacity to secrete proteins into the culture medium, growth in relatively simple substrates and robust post-translational machinery, among others, are presented as promising alternatives for the creation and establishment of these systems. Currently, these organisms produce a wide range of proteins, such as glycosidases, lipases, and proteases, for example. Scientific and technological development has increasingly allowed the evolution of molecular biology techniques that facilitate the genetic modification of organisms, thus, stimulating the establishment of new protein production systems. Amongst these techniques, it is possible to highlight the CRISPR/Cas system, a relatively simple, low-cost, and high-efficient tool for genetic modifications. Filamentous fungi, organisms widely used for protein production, have been used in a relatively low number of studies related to the production of (hemi-)cellulases using the CRISPR/Cas system as a genomic editing tool. (Hemi-)cellulases, enzymes that catalyze the breakdown of saccharides, are a class of enzymes that are highly researched and applied in several biotechnological areas in order to obtain a wide range of value-added bioproducts, such as bioethanol, for example. In this context, this review aims to illustrate the scenario of the application of the CRISPR/Cas technique for the production of (hemi-)cellulases, highlighting the main studies to date and the perspectives of a market that tends to grow exponentially in the coming years.