Bacterial Diversity in Deep-Sea Sediments of the North Atlantic Ocean and Their Biosynthesis of Secondary Metabolites

Abstract

Oceanic bathyal benthos harbours extremotolerant microbial species living with low nutrient availability, high hydrostatic pressure, and low temperature. Within their community, bacteria can secrete signalling molecules to gain a competitive advantage over space and nutrients, often representing bioactive compounds with relevant biotechnological potential. In this study, we investigate the species diversity of culturable bacteria associated with sediments sampled at the deepest margin of the European Western Continental Shelf. Furthermore, we explore their biosynthesis of known and new bioactive molecules. We isolated 144 bacterial strains belonging to 60 different taxa, including potentially new species, two species never recorded in the marine environment, and 15 new to the deep-sea. Investigation of the bacteria ability to synthesise ecologically relevant molecules was performed through genetic screening and metabolomics. Our results highlight a high rate of antibiotic-producing bacteria as well as the biosynthesis of potentially quorum-sensing compounds. Actinobacteria displayed the highest potential to biosynthesise bioactive molecules such as polyketides and non-ribosomal peptides, with a high rate of isolates carrying biosynthetic genes as well as the highest number of molecules detected by mass spectrometry. In this study, the deep-sea demonstrates a valuable source of unknown microbial and chemical diversity, supporting initiatives aimed at its protection from anthropogenic disturbance.