Constitutive hyperproduction of sorbicillinoids in Trichoderma reesei ZC121

Abstract

BackgroundIn addition to its outstanding cellulase production ability, Trichoderma reesei produces a wide variety of valuable secondary metabolites, the production of which has not received much attention to date. Among them, sorbicillinoids, a large group of hexaketide secondary metabolites derived from polyketides, are drawing a growing interest from researchers because they exhibit a variety of important biological functions, including anticancer, antioxidant, antiviral, and antimicrobial properties. The development of fungi strains with constitutive, hyperproduction of sorbicillinoids is thus desired for future industry application but is not well-studied. Moreover, although T. reesei has been demonstrated to produce sorbicillinoids with the corresponding gene cluster and biosynthesis pathway proposed, the underlying molecular mechanism governing sorbicillinoid biosynthesis remains unknown.ResultsRecombinant T. reesei ZC121 was constructed from strain RUT-C30 by the insertion of the gene 12121-knockout cassette at the telomere of T. reesei chromosome IV in consideration of the off-target mutagenesis encountered during the unsuccessful deletion of gene 121121. Strain ZC121, when grown on cellulose, showed a sharp reduction of cellulase production, but yet a remarkable enhancement of sorbicillinoids production as compared to strain RUT-C30. The hyperproduction of sorbicillinoids is a constitutive process, independent of culture conditions such as carbon source, light, pH, and temperature. To the best of our knowledge, strain ZC121 displays record sorbicillinoid production levels when grown on both glucose and cellulose. Sorbicillinol and bisvertinolone are the two major sorbicillinoid compounds produced. ZC121 displayed a different morphology and markedly reduced sporulation compared to RUT-C30 but had a similar growth rate and biomass. Transcriptome analysis showed that most genes involved in cellulase production were downregulated significantly in ZC121 grown on cellulose, whereas remarkably all genes in the sorbicillinoid gene cluster were upregulated on both cellulose and glucose.ConclusionA constitutive sorbicillinoid-hyperproduction strain T. reesei ZC121 was obtained by off-target mutagenesis, displaying an overwhelming shift from cellulase production to sorbicillinoid production on cellulose, leading to a record for sorbicillinoid production. For the first time, T. reesei degraded cellulose to produce platform chemical compounds other than protein in high yield. We propose that the off-target mutagenesis occurring at the telomere region might cause chromosome remodeling and subsequently alter the cell structure and the global gene expression pattern of strain ZC121, as shown by phenotype profiling and comparative transcriptome analysis of ZC121. Overall, T. reesei ZC121 holds great promise for the industrial production of sorbicillinoids and serves as a good model to explore the regulation mechanism of sorbicillinoids’ biosynthesis.Electronic supplementary materialThe online version of this article (10....

The G-protein Coupled Receptor GPR8 Regulates Secondary Metabolism in Trichoderma reesei

“…In agreement with this finding, YPR2, one of the transcription factors within the SOR cluster, impacts both carbon and secondary metabolism (Hitzenhammer et al, 2019). Also in a random mutant, increase in sorbicillinoid production accompanied with a decrease in cellulase production was observed, although the regulatory basis for this effect was not investigated (Li et al, 2018). Investigations of the function of YPR2 upon growth on glucose further support a carbon source dependent role of this transcription factor (Derntl et al, 2016).…”

Global Reprogramming of Gene Transcription in Trichoderma reesei by Overexpressing an Artificial Transcription Factor for Improved Cellulase Production and Identification of Ypr1 as an Associated Regulator

“…This crosslink is also reflected in the transcription factor Xpp1 in T. reesei , the presence of Xpp1 can inhibit the synthesis of hemicellulase genes and inhibit the production of secondary metabolites in the cell, which acts as a switch function between the primary and secondary metabolism (Derntl et al, 2017b ). Moreover, T. reesei ZC121 with up-regulated Ypr1 could overproduce the yellow pigment, but almost produce no extracellular cellulase (Li et al, 2018 ).…”

Novel Water-Soluble Photosensitizer for Photodynamic Inactivation of Gram-Positive Bacteria Using Nontoxic Dose of UV Light

“…Sorbicillinoids was produced from the fermentation of the recombinant Trichoderma reesei (T. reesei) strain ZC121 with an excellent sorbicillinoids production ability 40 . The obtained sorbicillinoids mainly included sorbicillinol, bisvertinolone and oxosorbicillinol as identified by LC-MS [40].…”

“…Sorbicillinoids was produced from the fermentation of the recombinant Trichoderma reesei (T. reesei) strain ZC121 with an excellent sorbicillinoids production ability 40 . The obtained sorbicillinoids mainly included sorbicillinol, bisvertinolone and oxosorbicillinol as identified by LC-MS [40]. Given that sorbicillinoids has great absorbance at 370 nm [41], there is a possibility that sorbicillinoids can generate 1 O 2 under light irradiation.…”