Open WL Archief (OWA)

Background

Jellyfish blooms represent a significant but largely overlooked source of labile organic matter (jelly-OM) in the ocean, characterized by a high protein content. Decaying jellyfish are important carriers for carbon export to the ocean’s interior. To accurately incorporate them into biogeochemical models, the interactions between microbes and jelly-OM have yet to be fully characterized. We conducted jelly-OM enrichment experiments in microcosms to simulate the scenario experienced by the coastal pelagic microbiome after the decay of a jellyfish bloom. We combined metagenomics, endo- and exo-metaproteomic approaches to obtain a mechanistic understanding on the metabolic network operated by the jelly-OM degrading bacterial consortium.

Results

Our analysis revealed that OM released during the decay of jellyfish blooms triggers a rapid shuffling of the taxonomic and functional profile of the pelagic bacterial community, resulting in a significant enrichment of protein/amino acid catabolism-related enzymes in the jelly-OM degrading community dominated by Pseudoalteromonadaceae, Alteromonadaceae and Vibrionaceae, compared to unamended control treatments. In accordance with the proteinaceous character of jelly-OM, Pseudoalteromonadaceae synthesized and excreted enzymes associated with proteolysis, while Alteromonadaceae contributed to extracellular hydrolysis of complex carbohydrates and organophosphorus compounds. In contrast, Vibrionaceae synthesized transporter proteins for peptides, amino acids and carbohydrates, exhibiting a cheater-type lifestyle, i.e. benefiting from public goods released by others. In the late stage of jelly-OM degradation, Rhodobacteraceae and Alteromonadaceae became dominant, growing on jelly-OM left-overs or bacterial debris, potentially contributing to the accumulation of dissolved organic nitrogen compounds and inorganic nutrients, following the decay of jellyfish blooms.

Conclusions