Abstract

The outstanding hydrolytic potential of the Planctomycetota phylum for complex polysaccharide degradation has recently been acknowledged based on the numerous carbohydrate-active enzymes (CAZymes) encoded in their genomes. However, mainly members of the Planctomycetia class have been characterised up to now, and little is known about the degrading capacities of the other Planctomycetota. Our in-depth characterisation of the available planctomycetotal genomic resources increased our knowledge of the carbohydrolytic capacities of Planctomycetota. We showed that this single phylum encompasses a wide variety of the currently known CAZyme diversity assigned to glycoside hydrolase families, and that many members are characterised by a high versatility towards complex carbohydrate degradation, including lignocellulose. We also highlighted members of the Isosphaerales, Pirellulales, Sedimentisphaerales and Tepidisphaerales orders as having the highest encoded hydrolytic potential of the Planctomycetota. Furthermore, members of a yet uncultivated group affiliated to Phycisphaerales were identified as an interesting source of novel, lytic polysaccharide monooxygenases that could boost lignocellulose degradation. Surprisingly, many Planctomycetota from anaerobic digestion reactors were shown to encode CAZymes targeting algal polysaccharides - this opens new perspectives for algal biomass valorisation in biogas processes. Our study provides a new perspective on planctomycetotal carbohydrolytic potential, highlighting distinct phylogenetic groups which could provide a wealth of diverse, potentially novel CAZymes of industrial interest.