Project image displaying the sea

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

Under certain conditions, viruses can become enriched in the sea-surface microlayer, a <1 mm thin habitat at the air-sea interface of aquatic ecosystems, but the role of microlayer viruses (‘the virioneuston’) for the microbial loop and carbon cycling at the sea surface is largely unknown. The project aims to characterize virus-host interactions within sea surface slicks by using a combinatory approach of cultivation experiments, microscopic and metagenomic analyses.

Project information

Project manager
Janina Rahlff, Karin Holmfeldt
Participating organizations
Linnaeus University
German Research Foundation (DFG)
March 2021–Feb 2023
Ecology (Department of Biology and Environmental Science, Faculty of Health and Life Sciences)

More about the project

Viruses in the sea-surface microlayer (SML), a <1 mm thin boundary layer between ocean and atmosphere, are highly understudied components in the marine realm. Frequent enrichment of viruses in this habitat compared to the underlying water, the tendency to form distinct communities as well as their appearance on particles and sea-spray aerosols allow to conclude that viruses in the SML could have an important role in the regulation of air-sea exchange processes.

It is likely that bacteriophage from the SML, belonging to the so-called virioneuston, can affect biogeochemical carbon cycling by frequent host cell lysis (induction of the viral shunt=carbon release due to cell lysis) and jump-start the microbial loop from the air-sea interface in contrast to the common belief that processes of the microbial loop begin in the upper water column.

VIBOCAT aims to provide insights into the role of bacteriophages in the SML by using state-of-the-art -omics, visualization, and cultivation methods. The objectives of the project are to study the prevailing infection mechanism of phages in the SML (lytic or lysogenic) and thus to judge their potential to induce the viral shunt. For this purpose, SML samples will be collected from the Baltic Sea and used for extraction and genome sequencing of at least three bacteriophage-host systems (first time for a marine SML) and for sequencing metagenomes (first time for a field SML). Samples for metagenomes will be collected from a very calm sea surface, a slick, usually enriched in organic material and compared to non-slick SML and the underlying water. Cultivation experiments and transmission electron microscopy analysis will be used to estimate lytic behavior and morphology of SML-extracted phages, respectively.

In summary, the project VIBOCAT will benefit our understanding of bacterial-viral interactions in the ocean-atmosphere boundary layer and reveal impacts of the virioneuston on microbial loop and carbon cycling in the ocean.

The project is part of Linnaeus Knowledge Environment: Water.