Synergy in viral–bacterial co-infection expedites algal bloom demise
Algal blooms are hotspots for diverse microbial interactions affecting bloom dynamics. Viral infections often regulate the demise of these blooms, recycling >25% of oceanic fixed carbon. Although these blooms collapse synchronously, only 10-30% of algal cells show active viral infection, suggesting additional mortality agents. Using microbial communities from natural coccolithophore blooms, we discovered that bacteria significantly enhanced virus-mediated algal mortality. We quantified this interaction using two novel metrics: the Synergy Index (SI) measuring viral-bacterial interaction strength, and the Benefit Index (BI) assessing changes in bacterial fitness. We identified Alteromonas bacteria as drivers of viral-bacterial coinfection, with consistently high SI and BI. In natural communities, Alteromonas exhibited chemoattraction towards infected algal cells, leading to their enrichment in bloom demise particles. This viral-bacterial synergy represents a previously unrecognized mortality agent controlling bloom termination, modulating the balance between the carbon-recycling viral shunt and the carbon-exporting viral shuttle pathways, likely influencing global carbon cycling.
Authors
- David Zeevi (ORCID: https://orcid.org/0000-0002-6492-6078)
- Guy Schleyer (ORCID: https://orcid.org/0000-0001-9756-9356)
- Inbal Nussbaum
- Roman Stocker (ORCID: https://orcid.org/0000-0002-3199-0508)
- Noa Barak-Gavish (ORCID: https://orcid.org/0000-0002-3881-884X)
- Assaf Vardi (ORCID: https://orcid.org/0000-0002-7079-0234)
- Estelle E. Clerc (ORCID: https://orcid.org/0009-0003-6046-2856)
- Constanze Kuhlisch (ORCID: https://orcid.org/0000-0002-7823-5382)
- Jean‐Baptiste Raina (ORCID: https://orcid.org/0000-0002-7508-0004)
- Nir Joffe (ORCID: https://orcid.org/0009-0001-3707-376X)
- Daniella Schatz (ORCID: https://orcid.org/0000-0003-2740-8391)
- Eliran Soffer
- Tal Sharon Nir-Zadock
- Guy Tadmor
Institutions
- Centre National de la Recherche Scientifique (FR)
- Université de Perpignan (FR)
- École Pratique des Hautes Études (FR)
- Université Paris Sciences et Lettres (FR)
- ETH Zurich (CH)
- Royal Netherlands Institute for Sea Research (NL)
- Centre de Recherches Insulaires et Observatoire de l'Environnement (PF)
- Institute of Environmental Engineering (CH)
- Institute of Microbiology (CH)
- Weizmann Institute of Science (IL)
Publication Details
- Journal
- Nature
- Published
- 2026-11-04
- DOI
- https://doi.org/10.1038/s41586-026-11243-7
- Citations
- 2
- Primary Topic
- Bacteriophages and microbial interactions
- Type
- article
- Field-Weighted Citation Impact
- 5.61
Funders
- European Commission