Biotechnology Bulletin ›› 2026, Vol. 42 ›› Issue (11): 45-57.doi: 10.13560/j.cnki.biotech.bull.1985.2025-1444

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Research Progress of AA9 Family Lytic Polysaccharide Monooxygenases

LI Cong1,2, YU Ru-yun2, ZHENG Fei2(), GUO Yu-jie1()   

  1. 1.Comprehensive Key Laboratory of Agro-products Processing, Ministry of Agriculture and Rural Affairs, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing 100193
    2.College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083
  • Received:2025-12-28 Online:2026-11-26 Published:2026-11-03
  • Contact: ZHENG Fei, GUO Yu-jie E-mail:zhengfei0718@bjfu.edu.cn;guoyujie@caas.cn

Abstract:

Lytic polysaccharide monooxygenases (LPMOs) can cleave glycosidic bonds in polysaccharide chains such as cellulose through oxidative cleavage. When acting synergistically with glycoside hydrolases in lignocellulose degradation, LPMOs significantly enhance sugar release efficiency, playing a crucial role in lignocellulosic biomass conversion. Among them, fungal LPMOs from the AA9 family exhibit broad substrate spectra and excellent oxidative activity, demonstrating great application potential in the food, energy, and materials industries. This review systematically summarizes the diversity of sources and functions of AA9 family LPMOs, highlighting that LPMOs from different origins exhibit marked differences in their promoting effects on glycoside hydrolases and substrate degradation patterns. In-depth structural analysis reveals that the Loop regions on the surface of the catalytic domain play a central regulatory role in substrate recognition, binding, and regioselectivity of oxidation. Additionally, in multi-domain LPMOs, the carbohydrate-binding module (CBM) significantly influences the process of substrate binding. Furthermore, this review compares the principles and applicability of various activity measurement methods, including MALDI-TOF-MS, HPAEC-PAD, and colorimetric assays, indicating that combined chromatography-mass spectrometry strategies are among the most widely used approaches for the quantitative analysis of LPMO oxidation products. Finally, the considerable application potential of LPMOs in food processing, bioenergy, and nanocellulose preparation is discussed in detail. Therefore, the discovery of novel LPMO enzymes or the molecular engineering of existing ones to obtain new enzyme preparations more suitable for industrial applications is an important direction for current research. Moreover, this review deeply analyzes the key technical challenges in current AA9 family LPMO research, including functional characterization of enzyme resources, elucidation of the molecular mechanisms underlying substrate specificity, and improvement of practical application efficiency. Targeted future research directions and strategic suggestions are proposed, such as mining novel enzymes using metagenomics, integrating structural prediction and machine learning to analyze substrate selectivity, and performing targeted enzyme molecular engineering tailored to different pretreatment processes. This review aims to provide a theoretical reference for the development, application, and molecular engineering of AA9 family LPMOs.

Key words: lytic polysaccharide monooxygenase, AA9 family, functional regulation mechanism, oxidative regioselectivity, synergistic catalysis, activity assay, industrial application