Enhanced cellulase production in Trichoderma reesei RUT C30 via constitution of minimal transcriptional activators

Abstract

BackgroundCellulase can convert lignocellulosic feedstocks into fermentable sugars, which can be used for the industrial production of biofuels and chemicals. The high cost of cellulase production remains a challenge for lignocellulose breakdown. Trichoderma reesei RUT C30 serves as a well-known industrial workhorse for cellulase production. Therefore, the enhancement of cellulase production by T. reesei RUT C30 is of great importance.ResultsTwo sets of novel minimal transcriptional activators (DBDace2-VP16 and DBDcre1-VP16) were designed and expressed in T. reesei RUT C30. Expression of DBDace2-VP16 and DBDcre1-VP16 improved cellulase production under induction (avicel or lactose) and repression (glucose) conditions, respectively. The strain TMTA66 under avicel and TMTA139 under glucose with the highest cellulase activities outperformed other transformants and the parental strain under the corresponding conditions. For TMTA66 strains, the highest FPase activity was approximately 1.3-fold greater than that of the parental strain RUT C30 at 120 h of cultivation in a shake flask using avicel as the sole carbon source. The FPase activity (U/mg biomass) in TMTA139 strains was approximately 26.5-fold higher than that of the parental strain RUT C30 at 72 h of cultivation in a shake flask using glucose as the sole carbon source. Furthermore, the crude enzymes produced in the 7-L fermenter from TMTA66 and TMTA139 supplemented with commercial β-glucosidase hydrolyzed pretreated corn stover effectively.ConclusionsThese results show that replacing natural transcription factors with minimal transcriptional activators is a powerful strategy to enhance cellulase production in T. reesei. Our current study also offers an alternative genetic engineering strategy for the enhanced production of industrial products by other fungi.Electronic supplementary materialThe online version of this article (10.1186/s12934-018-0926-7) contains supplementary material, which is available to authorized users.

Precision engineering of the transcription factor Cre1 inHypocrea jecorina (Trichoderma reesei)for efficient cellulase production in the presence of glucose

“…Thus, several attempts were made to alleviate CCR by introducing modifications in Cre1 for improving cellulase production. It was proved that replacement of the endogenous transcription factor Cre1/CreA by an artificial minimal transcriptional activator, such as Cre1-96 or other Cre1/CreA mutants, leads to release or attenuation of CCR, which in turn is supports cellulase production efficiency in T. reesei or A. nidulans (Shroff et al, 1997;Mello-de-Sousa et al, 2014;Rassinger et al, 2018;Zhang et al, 2018). However, Liu et al (2019) demonstrated that full-length Cre1 might be necessary for the rapid growth of T. reesei.…”

Co-culture of Vel1-overexpressed Trichoderma asperellum and Bacillus amyloliquefaciens: An eco-friendly strategy to hydrolyze the lignocellulose biomass in soil to enrich the soil fertility, plant growth and disease resistance

“…Cellulase production by the mono and co-culture For the mono-culture, T. asperellum (TA) (10 6 /mL spores) or the recombinant T. asperellum (TA OE-Vel1) (10 6 /mL spores) were cultured in the minimal broth containing 2% avicel as described by [35]. For co-cultivation, 0.1% of the B. amyloliquefaciens 1841 (BA) was added into the 48 th hour T. asperellum and recombinant T. asperellum pre-culture medium and named as TA+BA and TA OE-Vel1+BA respectively.…”

“…The endoglucanase (CMCase) activity was tested according to Bailey and Nevalainen [37]. Cellobiohydrolase (pNPCase), and β-glucosidase (pNPGase) were assessed by the methodology of Zhang et al [35]. Xylanase I and II were assessed at pH 3.7 and 5.0 respectively according to the method of Sticker et al [38].…”

“…The corn stover was pretreated by the method of Tsegaye et al [39]. The crude enzymes produced by four different methods were used to hydrolyze the lignocellulose biomassas suggested by Zhang et al [35]. The glucose content of the hydrolysate were estimated according to the method of Li et al [40].…”

Engineering the Effector Domain of the Artificial Transcription Factor to Improve Cellulase Production by Trichoderma reesei

“…On the other hand, artificial transcription factors (ATFs) have also been studied to genetically engineer cellulase production. For example, the repressor Cre1 could be changed to transcriptional activator for cellulases gene expression by replacement of the VP 16 activation domain (AD) (Zhang J. et al, 2018). In the previous studies, a library of artificial zinc finger proteins (AZFPs) was explored for expression in bacteria and yeast (Park et al, 2003;Ma et al, 2015), and screened for mutants with changed phenotypes.…”