Biosynthetic gene clusters (BGCs) which encode diverse secondary metabolites are ubiquitous across microbiomes and support critical ecological functions. They also serve as attractive targets for new drug discovery. Here we combined genome-resolved metagenomics with long-read Nanopore RNA sequencing, yielding 1016 bacterial and 124 archaeal medium-to-high quality MAGs from previously unchartered microbial communities in Arctic hydrothermal vent biofilms. We identified 2965 BGCs from 870 metagenome-assembled genomes (MAGs) comprising a distinctive and rich diversity of BGCs, with ribosomally synthesized and post-translationally modified peptides (RiPPs) predominating across all samples. RiPPs and non-ribosomal peptide synthetases (NRPs), also known to encode metabolites with antimicrobial potential, are represented among the most expressed transcripts. Terpenes, though less expressed, contribute to microbial signaling and defense. Notably, we identify hydrogen cyanide (HCN) synthesis pathways in archaeal genomes, challenging the view that cyanogenesis is restricted to bacteria and eukaryotes. Our findings demonstrate that microbial adaptation to extreme environments favors RiPP-based biosynthesis and that HCN may play a role in archaeal ecological interactions. Moreover, microbial communities in Arctic hydrothermal vent biofilms provide a rich reservoir of unique bioactive compounds, with implications for drug discovery.
Thuc Trong Nguyen, I. H. Steen, R. Stokke· Nature Communications· 0 citations
Smaragdinella marine snails are the only members of the family Haminoeidae and the order Cephalaspidea that inhabit hard substrates in the upper tidal zone, making them of special evolutionary interest. To investigate whether possible novel trophic adaptations coupled with unique morphological traits may underlie this ecological shift, we analysed the gut contents and microbiota of Smaragdinella viridis using DNA metabarcoding (COI and 16S rRNA) and scanning electron microscopy (SEM). COI metabarcoding revealed a diverse assemblage of dietary components dominated by diatoms, rotifers, small arthropods, and fungi. SEM observations partially corroborated these findings, indicating an omnivorous feeding strategy rather than strict herbivory. The gut bacterial community was dominated by Firmicutes (Mycoplasma), Proteobacteria (Vibrio, Photobacterium), and Fusobacteriota (Psychrilyobacter, Propionigenium), taxa associated with the degradation of complex carbohydrates and proteins. Morphological traits in Smaragdinella, including an increased number of gizzard plate ridges, a flattened ovoid shell, and an enlarged foot, most likely facilitate the processing of diverse food items and survival in wave-exposed environments. In addition, the functionality of the gut microbiome may contribute to dietary flexibility enhancing survival in dynamic, resource-variable tidal habitats. The adaptation of these snails to tidal hard bottom habitats could have been prompted by the acquisition of novel morphological features and by a diet shift, but the data do not permit to establish a causal relationship and alternative hypotheses may have to be considered.
Monisha Bharate-Grevskott, J. Hestetun, I. Steen et al.· Scientific Reports· 0 citations
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