Inducer-free cellulase production system based on the constitutive expression of mutated XYR1 and ACE3 in the industrial fungus Trichoderma reesei.

Trichoderma reesei is a widely used host for producing cellulase and hemicellulase cocktails for lignocellulosic biomass degradation. Here, we report a genetic modification strategy for industrial T. reesei that enables enzyme production using simple glucose without inducers, such as cellulose, lactose and sophorose.

Nuclear export-dependent degradation of the carbon catabolite repressor CreA is regulated by a region located near the C-terminus in Aspergillus oryzae.

Carbon catabolite repression (CCR) is regulated by the C H -type transcription factor CreA/Cre1 in filamentous fungi including Aspergillus oryzae. We investigated the stability and subcellular localization of CreA in A. oryzae.

Increased production of biomass-degrading enzymes by double deletion of creA and creB genes involved in carbon catabolite repression in Aspergillus oryzae.

In a previous study, we reported that a double gene deletion mutant for CreA and CreB, which constitute the regulatory machinery involved in carbon catabolite repression, exhibited improved production of α-amylase compared with the wild-type strain and single creA or creB deletion mutants in Aspergillus oryzae. Because A. oryzae can also produce biomass-degrading enzymes, such as xylolytic and cellulolytic enzymes, we examined the production levels of those enzymes in deletion mutants in this study.

Cell wall α-1,3-glucan prevents α-amylase adsorption onto fungal cell in submerged culture of Aspergillus oryzae.

We have previously reported that α-amylase (Taka-amylase A, TAA) activity disappears in the later stage of submerged Aspergillus oryzae culture as a result of TAA adsorption onto the cell wall. Chitin, one of the major components of the cell wall, was identified as a potential factor that facilitates TAA adsorption. However, TAA adsorption only occurred in the later stage of cultivation, although chitin was assumed to be sufficiently abundant in the cell wall regardless of the submerged culture period.

Cellular responses to the expression of unstable secretory proteins in the filamentous fungus Aspergillus oryzae.

Filamentous fungi are often used as cell factories for recombinant protein production because of their ability to secrete large quantities of hydrolytic enzymes. However, even using strong transcriptional promoters, yields of nonfungal proteins are generally much lower than those of fungal proteins. Recent analyses revealed that expression of certain nonfungal secretory proteins induced the unfolded protein response (UPR), suggesting that they are recognized as proteins with folding defects in filamentous fungi.

Distinct mechanism of activation of two transcription factors, AmyR and MalR, involved in amylolytic enzyme production in Aspergillus oryzae.

The production of amylolytic enzymes in Aspergillus oryzae is induced in the presence of starch or maltose, and two Zn2Cys6-type transcription factors, AmyR and MalR, are involved in this regulation. AmyR directly regulates the expression of amylase genes, and MalR controls the expression of maltose-utilizing (MAL) cluster genes. Deletion of malR gene resulted in poor growth on starch medium and reduction in α-amylase production level.

Improved α-amylase production by Aspergillus oryzae after a double deletion of genes involved in carbon catabolite repression.

In filamentous fungi, the expression of secretory glycoside hydrolase encoding genes, such as those for amylases, cellulases, and xylanases, is generally repressed in the presence of glucose. CreA and CreB have been observed to be regulating factors for carbon catabolite repression. In this study, we generated single and double deletion creA and/or creB mutants in Aspergillus oryzae.