Every road leads to Rome: diverse biosynthetic regulation of plant cell wall-degrading enzymes in filamentous fungi Penicillium oxalicum and Trichoderma reesei

Abstract

Cellulases and xylanases are plant cell wall-degrading enzymes (CWDEs) that are critical to sustainable bioproduction based on renewable lignocellulosic biomass to reduce carbon dioxide emission. Currently, these enzymes are mainly produced from filamentous fungi, especially Trichoderma reesei and Penicillium oxalicum. However, an in-depth comparison of these two producers has not been performed. Although both P. oxalicum and T. reesei harbor CWDE systems, they exhibit distinct features regulating the production of these enzymes, mainly through different transcriptional regulatory networks. This review presents the strikingly different modes of genome-wide regulation of cellulase and xylanase biosynthesis in P. oxalicum and T. reesei, including sugar transporters, signal transduction cascades, transcription factors, chromatin remodeling, and three-dimensional organization of chromosomes. In addition, different molecular breeding approaches employed, based on the understanding of the regulatory networks, are summarized. This review highlights the existence of very different regulatory modes leading to the efficient regulation of CWDE production in filamentous fungi, akin to the adage that “every road leads to Rome.” An understanding of this divergence may help further improvements in fungal enzyme production through the metabolic engineering and synthetic biology of certain fungal species.

Keywords:

• Cellulase
• xylanase
• plant cell wall-degrading enzymes
• Penicillium oxalicum
• Trichoderma reesei
• regulatory networks
• metabolic engineering
• lignocellulosic biomass
• synthetic biology

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 [U21A20178; 32060022; 32060141], the State Key Research and Development Program of China [2021YFC2101302; 2021YFC2103004], Key Research and Development Program Project of Guangxi [Guike AB21076010], the Autonomous Research Project of State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources [SKLCUSA-a202209], Training Program for 1000 Young and Middle-aged Key Teachers in Guangxi at 2019.