Servicenavigation

Project Details

Back

Projekt Print View

Exploring the virioneuston: Viral-bacterial interactions between ocean and atmosphere (VIBOCAT)

Applicant Dr. Janina Rahlff
Subject Area Microbial Ecology and Applied Microbiology
Term from 2020 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 446702140
 
Final Report Year 2024

Final Report Abstract

Viruses in the sea surface microlayer (SML), a <1 mm thin film between the ocean and the atmosphere, are poorly understood components of the marine environment. The frequent enrichment of viruses in the SML compared to deeper water layers, the tendency to form distinct communities as observed in freshwater studies, and their presence on particles and in seawater aerosols suggest that SML viruses play a crucial role in regulating air-water exchange processes. Utilizing state-of-the-art -omics, visualization, and cultivation methods, this project further investigated the role of bacteriophages in the SML. The project objectives included elucidating the infection mechanisms of SML phages (lytic or lysogenic) to estimate the potential of phages to initiate the "viral shunt" in the SML. Additionally, the significance of particles in the SML for viruses was examined. SML samples were collected in the Baltic Sea, new phage-host systems were explored, and metagenomes were sequenced, and cell and virus particle numbers determined. A quiescent sea surface, a so-called "slick," was compared to a non-slick SML and the underlying water. Through size-fractionated filtration, also particle-associated and nonparticle-associated viral-bacterial communities were investigated. Distinct viral-bacterial communities formed in the short-lived slick compared to reference samples, and lytic phages were found and isolated for abundant slick Gammaproteobacteria (Pseudoalteromonas tunicata, Rheinheimera baltica, Alishewanella sp.). Metagenomic analyses of viral microdiversity showed that virus variants were mainly present in particle-associated samples (>5 µm), regardless of water depth (SML or underlying water). CRISPR analyses revealed virus-host relationships in the slick SML that were decoupled from the non-slick SML and the underlying water. Further analyses of bacterial genomes showed genes for motility, quorum sensing, and biofilm formation in the slick SML. According to their usage profiles, abundant bacterial isolates exhibited different carbon preferences, likely facilitating their coexistence in the slick. The same applied to genomes assembled from metagenomes of abundant compared to less abundant slick bacteria. Prophages were scarce in bacterial genomes (4), but evidence indicated prophage induction in the abundant Alishewanella sp., suggesting that virus lysis prevails in the slick and can contribute to the viral shunt, supported by a large amount of dissolved carbon in the slick. In summary, the VIBOCAT project has improved our understanding of viral-bacterial interactions in the air-sea boundary layer, providing insights into influences on the microbial loop and carbon fluxes in the sea.

Publications

 
 

Additional Information

© 2026 DFG Disclaimer / Copyright / Privacy Policy

Textvergrößerung und Kontrastanpassung