Defining the ecological strategies of phytoplankton associated bacteria

Abstract Ecological interactions between phytoplankton and bacteria govern the productivity and biogeochemistry of aquatic ecosystems. However, our understanding of these partnerships primarily comes from laboratory-based model systems, meaning that little is known about the establishment and dynami...

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Main Authors: Amaranta Focardi, Anna R. Bramucci, Penelope Ajani, Abeeha Khalil, Jean-Baptiste Raina, Justin R. Seymour
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-61523-5
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author Amaranta Focardi
Anna R. Bramucci
Penelope Ajani
Abeeha Khalil
Jean-Baptiste Raina
Justin R. Seymour
author_facet Amaranta Focardi
Anna R. Bramucci
Penelope Ajani
Abeeha Khalil
Jean-Baptiste Raina
Justin R. Seymour
author_sort Amaranta Focardi
collection DOAJ
description Abstract Ecological interactions between phytoplankton and bacteria govern the productivity and biogeochemistry of aquatic ecosystems. However, our understanding of these partnerships primarily comes from laboratory-based model systems, meaning that little is known about the establishment and dynamics of these interactions. Here, we tracked the development of the microbiome of 15 newly isolated phytoplankton species for 400 days. After only 20 days, each phytoplankton harboured a unique bacterial assemblage. Within these assemblages, we identify (i) specialist phytoplankton associates, which are bacteria that establish long-term interactions with 1-2 phytoplankton strains; (ii) generalists, which are associated with 3 or more phytoplankton strains; and (iii) transients, which do not develop sustained associations with any phytoplankton strains. Compared to transients, the generalists and specialists are enriched in genes involved in chemotaxis, vitamin synthesis, secondary metabolite production and the ability to uptake specific phytoplankton-derived compounds. Moreover, generalists display greater potential to move between hosts and release antimicrobials. Finally, examination of co-occurrence patterns in oceanographic time-series revealed that generalists and specialists mirror their phytoplankton partner’s abundance in the environment. The divergent genomic characteristics of these discrete bacterial categories highlight different ecological strategies that likely shape phytoplankton microbiomes.
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spelling doaj-art-0663701b9ac7432ebc2fdd3a4a77ee102025-08-20T03:43:14ZengNature PortfolioNature Communications2041-17232025-07-0116111310.1038/s41467-025-61523-5Defining the ecological strategies of phytoplankton associated bacteriaAmaranta Focardi0Anna R. Bramucci1Penelope Ajani2Abeeha Khalil3Jean-Baptiste Raina4Justin R. Seymour5Climate Change Cluster (C3), University of Technology SydneyClimate Change Cluster (C3), University of Technology SydneySchool of Life Sciences, University of Technology SydneyClimate Change Cluster (C3), University of Technology SydneyClimate Change Cluster (C3), University of Technology SydneyClimate Change Cluster (C3), University of Technology SydneyAbstract Ecological interactions between phytoplankton and bacteria govern the productivity and biogeochemistry of aquatic ecosystems. However, our understanding of these partnerships primarily comes from laboratory-based model systems, meaning that little is known about the establishment and dynamics of these interactions. Here, we tracked the development of the microbiome of 15 newly isolated phytoplankton species for 400 days. After only 20 days, each phytoplankton harboured a unique bacterial assemblage. Within these assemblages, we identify (i) specialist phytoplankton associates, which are bacteria that establish long-term interactions with 1-2 phytoplankton strains; (ii) generalists, which are associated with 3 or more phytoplankton strains; and (iii) transients, which do not develop sustained associations with any phytoplankton strains. Compared to transients, the generalists and specialists are enriched in genes involved in chemotaxis, vitamin synthesis, secondary metabolite production and the ability to uptake specific phytoplankton-derived compounds. Moreover, generalists display greater potential to move between hosts and release antimicrobials. Finally, examination of co-occurrence patterns in oceanographic time-series revealed that generalists and specialists mirror their phytoplankton partner’s abundance in the environment. The divergent genomic characteristics of these discrete bacterial categories highlight different ecological strategies that likely shape phytoplankton microbiomes.https://doi.org/10.1038/s41467-025-61523-5
spellingShingle Amaranta Focardi
Anna R. Bramucci
Penelope Ajani
Abeeha Khalil
Jean-Baptiste Raina
Justin R. Seymour
Defining the ecological strategies of phytoplankton associated bacteria
Nature Communications
title Defining the ecological strategies of phytoplankton associated bacteria
title_full Defining the ecological strategies of phytoplankton associated bacteria
title_fullStr Defining the ecological strategies of phytoplankton associated bacteria
title_full_unstemmed Defining the ecological strategies of phytoplankton associated bacteria
title_short Defining the ecological strategies of phytoplankton associated bacteria
title_sort defining the ecological strategies of phytoplankton associated bacteria
url https://doi.org/10.1038/s41467-025-61523-5
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