The SuReMetS project assembled a comprehensive fosmid library from diverse aquatic habitats, including the North and Baltic Seas, deep‑sea samples, and microalgal microbiomes. DNA extraction was performed on existing microbiome samples and on new isolates from microalgae and fish, followed by quality assessment and construction of >50,000 fosmid clones with inducible replication origins. These libraries were stored in 96‑well plates at –80 °C and subjected to quality checks for fragment size and phylogenetic diversity before functional screening. In enrichment cultures of the brown alga *Fucus vesiculosus*, metagenomic sequencing revealed 69 146 972 protein‑coding genes after nine days of enrichment. The majority (91.6 ± 2.5 %) belonged to Pseudomonadota, with Bacillota, Fusobacteria, and Spirochaetes contributing smaller fractions. Bacteroidota, although less abundant, supplied the largest share of genes involved in algal cell‑wall degradation, particularly glycosyl‑hydrolase (GH) and sulfatase (S) families. Heat‑map analysis of GH and S families showed a pronounced enrichment of Bacteroidota‑derived genes, especially in families GH29, GH107, GH168, S1_17, and S1_25, which are implicated in fucoidan breakdown. Cluster‑analysis using Cytoscape confirmed that the highest number of putative GH genes originated from the Bacteroidota phylum, despite the dominance of Pseudomonadota in the overall community.

Functional expression of selected genes in *Escherichia coli* and *Pichia pastoris* yielded two thermostable α‑L‑fucosidases, FUJM18 and FUJM20. Induction assays in autoinduction medium ZYM5052 and SDS‑PAGE analysis demonstrated successful expression of the GH29 family enzymes. Activity testing revealed Z‑scores of 42.9 for both FUJM18 and FUJM20, compared with a reference α‑L‑fucosidase (6GN6) exhibiting a Z‑score of 51.6. Structural modeling suggested hexameric or multimeric assembly with a central active site, consistent with known fucosidase architectures. Parallel bioactivity assays evaluated the extracts for anti‑diabetic, antioxidant, and anti‑inflammatory properties, while scale‑up experiments optimized enzymatic hydrolysis of fish biomass and microalgal biorefinery processes at industrial scale, adjusting enzyme load, temperature, filtration, drying, and packaging parameters. A preclinical animal study, building on the in‑vitro screening results, assessed the potential of the novel marine compounds to mitigate hypertension, hyperglycaemia, dyslipidaemia, and excess adiposity, thereby addressing components of the metabolic syndrome.

Collaboration within SuReMetS involved multiple German research institutions. The University of Hamburg led the enrichment strategies, metagenomic, metatranscriptomic, and metaproteomic analyses, functional screening, and heterologous protein expression, leveraging its long‑standing expertise in marine biotechnology. Partner laboratories at the University of Cologne (UCC) and the University of Hamburg (UHH) contributed additional DNA extractions from microalgae and fish, and provided facilities for large‑scale biorefinery demonstrations. The project was structured into five work packages (AP 1–5), spanning from library construction and functional screening to preclinical evaluation, and was carried out over a multi‑year period under the SuReMetS umbrella. Funding was provided through the SuReMetS initiative, which supports transdisciplinary research combining basic marine biology, public health, and industrial biotechnology to develop marine nutraceuticals with high commercial potential.