Marine fungal enzymes as potential degraders of the diverse seaweed cell-walls

Abstract

Marine fungi play a critical yet understudied role in marine ecosystems, contributing to microbial diversity and ecological balance through their interactions with seaweed and other organisms. These interactions are essential for nutrient cycling and maintaining ecosystem health. While the carbohydrate-active enzymes (CAZymes) of terrestrial fungi are well-documented for plant biomass degradation, the enzymatic capabilities of marine fungi, specifically for degrading seaweed biomass, remain less explored. The distinct sugar composition of seaweed has likely shaped the CAZome of marine fungi, specifically in activities targeting seaweed cell wall polysaccharides. This review focuses on the potential of marine fungal CAZymes as biocatalysts for the degradation of seaweed cell wall polysaccharides. We provide a detailed examination of the unique sugar composition of seaweed cell walls, such as alginates, fucoidans, and carrageenans, and analyze the putative CAZy abilities of marine fungi to target these structures. A better understanding of marine fungal enzymatic processes could unlock sustainable strategies for extracting valuable compounds, such as proteins and nutraceuticals, from seaweed biomass, while enabling the comprehensive valorization of all biomass fractions within a biorefinery framework. By summarizing current knowledge and identifying research gaps, this review highlights the untapped potential of marine fungi as key agents in the development of efficient, integrated seaweed biorefineries.