Genomic Diversity of Carbohydrate-Active Enzymes in Marine-Associated Fungi

Marine-associated fungi harbor diverse repertoires of carbohydrate-active enzymes (CAZymes) involved in carbohydrate degradation, modification, and synthesis. However, the comparative genomic distribution of CAZymes across marine-associated fungal lineages remains poorly characterized. In this study, we compared the CAZyme repertoires of 27 marine-associated fungal proteomes using a standardized dbCAN workflow, complemented by published annotations for two additional isolates. Comparisons incorporated normalization to predicted proteome size and family prevalence, and non-metric multidimensional scaling based on Jaccard and Bray–Curtis dissimilarities. The standardized analysis detected 204 CAZy families, of which 28 were present in all 27 proteomes; the combined inventory, including literature-derived annotations, comprised 206 families. CAZyme protein counts ranged from 112 to 893, corresponding to 17.0–57.2 proteins per 1000 predicted proteins. Glycoside hydrolases represented the dominant CAZyme class in 25 of the 27 proteomes, although all six major CAZy classes were detected in every proteome. Both ordinations showed substantial overlap among isolation-source categories, without clear visual separation by source. Overall, the results reveal a shared subset of CAZy families alongside substantial variation among taxa in repertoire size, composition, and normalized representation. These patterns describe predicted carbohydrate-processing potential without establishing ecological specialization or substrate utilization. Here, we provide a comparative genomic framework to investigate the diversity and evolution of fungal carbohydrate-processing capacities and to guide future functional characterization of marine-associated fungal CAZymes.