Community and metagenomic dynamics reveal Bacteroidota's role in widespread enzymatic algae cell wall degradation

As green economies with a focus on novel, sustainable resources are growing, the need for novel biotechnological tools and enzymes is mandatory. The use of marine algae as source for drugs, food and energy still lacks of efficient processes to degrade the algae cell wall (ACW) for economic interests in up-scale applications. In this frame, we used in vitro enrichment cultures with the brown macroalgae Fucus vesiculosus to detect efficient, cell wall polymer degrading microbial communities and enzymes in combination with in silico screening using a high-performance, established enzyme screening pipelines with Hidden Markov Models (HMM). We were able to archive high-scale algae degradation in 20 days relying on a dynamic microbial community. Furthermore, the degradation potential of specific bacterial taxa in a changing community by analysing metagenome datasets during the enrichment process with 107 HMMs of enzyme families of glycosyl hydrolyses (GH) and sulfatases (S) revealed Bacteroidota as the main phyla in carbohydrate hydrolysation and identified 8,442 potential active enzymes. In contrast, Pseudomonadota genes made up over 90% of the whole bacterial community with 1,871 assigned genes belonging to the conducted HMMs. Since Bacteroidetes genes only made up around 1.5% of the microbial community, we conclude that the released sugar monomers as degradation products are metabolised more efficient by the Pseudomonadota community as by Bacteroidota, resulting in a suppression of the Bacteroidota and so an inhibited degradation. The implementation and testing of four active genes of the a-L-fucosidase enzyme family GH29 analysed by the HMM approach act as proof of concept offers novel enzymes for industrial, future application.