Engineering Trichoderma reesei for the hyperproduction of cellulose induced protein 1 (Cip1) on a sophorose-containing inducer to efficiently saccharify alkali-pretreated corn stover

Abstract

Trichoderma reesei was induced to produce cellulase by a combination of glucose and β-disaccharide; however, lower levels of auxiliary proteins for degrading lignocellulosic biomass were detected by iTRAQ analysis compared with cellulose as an inducer, especially cellulose induced protein 1 (CIP1). In this study, A pdc1 promoter-driven overexpression of the endogenous Trcip1 gene was observed in T. reesei Rut C30, and the Trcip1 transcription levels of the two transformants, T. reesei OE-cip1-1 and OE-cip1-2, demonstrated 31.2- and 164.6-fold increases, respectively, but there was no significant change in cellobiohydrolase, endoglucanase and filter paper activity at 48 h. The crude enzyme was then used to hydrolyze corn stover. For T. reesei OE-cip1-1 and OE-cip1-2, the hydrolysis efficiency increased by 25.0 and 28.6% with a solid loading of 5% at 2 h, respectively. Simultaneously, 85.5 and 85.2 g/L glucose were released using a cellulase cocktail at high solid loading (20%), and these glucose release rates were significantly greater than that of T. reesei Rut C30 cellulase (77.4 g/L) at 120 h. Furthermore, scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed that the enhanced hydrolysis efficiency was primarily triggered by the decrease in the crystallinity of lignocellulose, and the fiber structure had varying degrees of loosening and disintegration.

Keywords:

• Cellulase
• corn stover
• saccharification
• soluble inducer
• Trcip1
• Trichoderma reesei

Acknowledgments

The authors appreciate the helpful discussion with Ruimeng Gu at the Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences.

Informed consent

All authors consent to publish the manuscript.

Author contributions

Yonghao Li conceived the project. Jianghong Li performed the study. Yonghao Li, Jianghong Li, Yudian Chen, Yushan Gao, Yi Mo, and Tingting Long analyzed the data and drafted the manuscript. Bo Yao critically revised the manuscript. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [21808022], the Natural Science Foundation Project of Chongqing, Chongqing Science and Technology Commission (CN) [CSTB2022NSCQ-MSX0544], Postgraduate Research and Innovation Project of Chongqing [CYS22727], and also supported by Postgraduate Research and Innovation Project of Chongqing University of Science and Technology [YKJCX2120505 and YKJCX2120526].