Secondary metabolism in Irpex lacteus (Fr.) Fr.: biosynthetic logic and redox integration

Irpex lacteus is a metabolically versatile white-rot fungus capable of producing a wide range of structurally diverse secondary metabolites, including terpenoids, phenolics, steroids, peptides, and polysaccharides. Many of these compounds exhibit notable biological activities, such as antioxidant, antimicrobial, anti-inflammatory, and cytoprotective effects, highlighting their potential relevance to food chemistry and agricultural applications. Owing to its highly efficient ligninolytic enzyme system and flexible secondary metabolic network, I. lacteus has emerged as a promising biological platform for lignocellulose valorization, microbial biotransformation, and the discovery of functional food ingredients and natural preservatives. In recent years, significant progress has been made in elucidating the chemical diversity and biosynthetic logic of its characteristic metabolites, particularly tremulane-type sesquiterpenoids with unusual skeletal rearrangements. This review systematically summarizes 226 secondary metabolites reported from I. lacteus, covering their chemical classification, biosynthetic features, biotransformation capabilities, and biological activities. Special emphasis is placed on advances enabled by genome mining, heterologous expression, and co-culture strategies that activate cryptic biosynthetic pathways. Finally, the potential applications of I. lacteus metabolites in agriculture, food chemistry, and sustainable bioprocessing are discussed, and future perspectives based on multi-omics integration and metabolic engineering are proposed.