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Top-down structuring of freshwater bacterial communities by mixotrophic flagellates

Mixotrophic and heterotrophic protists hold a key position in aquatic microbial food webs. Whereas they can account for the bulk of bacterivory in pelagic systems, the potential structuring effect of these consumers on bacterial communities is far from clear. We conducted short-term grazing experime...

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Autores principales: Ivanković, Marina, Ptacnik, Robert, Bengtsson, Mia Maria
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10475056/
https://www.ncbi.nlm.nih.gov/pubmed/37660188
http://dx.doi.org/10.1038/s43705-023-00289-7
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author Ivanković, Marina
Ptacnik, Robert
Bengtsson, Mia Maria
author_facet Ivanković, Marina
Ptacnik, Robert
Bengtsson, Mia Maria
author_sort Ivanković, Marina
collection PubMed
description Mixotrophic and heterotrophic protists hold a key position in aquatic microbial food webs. Whereas they can account for the bulk of bacterivory in pelagic systems, the potential structuring effect of these consumers on bacterial communities is far from clear. We conducted short-term grazing experiments to test for the overall impact on bacterial community structure and possible prey preferences of phagotrophic protists. The protist taxa selected for this study include three mixotrophic flagellates, comprising two obligate- and one facultative mixotroph, and one phagoheterotrophic flagellate lacking phototrophic capacity. Bacterioplankton from seven different lakes were enriched and used to represent semi-natural prey communities. Our study demonstrated protist strain specific impacts on bacterial community composition linked to grazing. The three mixotrophs had variable impacts on bacterial communities where the two obligate mixotrophs exhibited lower grazing rates, while showing a tendency to promote higher bacterial diversity. The phagoheterotroph displayed the highest grazing rates and structured the bacterial communities via apparent selective grazing. Consistent selectivity trends were observed throughout the experiments, such as the apparent avoidance of all flagellates of Actinobacteria, and high grazing on dominant Burkholderiales taxa. However, there was no consistent “fingerprint” of mixotrophic grazing on prey communities, but the structuring impact rather seemed to depend on the trophic mode of the individual protist taxa, i.e. their dependence on phototrophy vs. phagotrophy. Our findings highlight the differential structuring impact of protist taxa on bacterial communities which may have important ecological implications, for example during periodic dominance of obligate mixotrophic bacterivores in changing lake ecosystems.
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spelling pubmed-104750562023-09-04 Top-down structuring of freshwater bacterial communities by mixotrophic flagellates Ivanković, Marina Ptacnik, Robert Bengtsson, Mia Maria ISME Commun Article Mixotrophic and heterotrophic protists hold a key position in aquatic microbial food webs. Whereas they can account for the bulk of bacterivory in pelagic systems, the potential structuring effect of these consumers on bacterial communities is far from clear. We conducted short-term grazing experiments to test for the overall impact on bacterial community structure and possible prey preferences of phagotrophic protists. The protist taxa selected for this study include three mixotrophic flagellates, comprising two obligate- and one facultative mixotroph, and one phagoheterotrophic flagellate lacking phototrophic capacity. Bacterioplankton from seven different lakes were enriched and used to represent semi-natural prey communities. Our study demonstrated protist strain specific impacts on bacterial community composition linked to grazing. The three mixotrophs had variable impacts on bacterial communities where the two obligate mixotrophs exhibited lower grazing rates, while showing a tendency to promote higher bacterial diversity. The phagoheterotroph displayed the highest grazing rates and structured the bacterial communities via apparent selective grazing. Consistent selectivity trends were observed throughout the experiments, such as the apparent avoidance of all flagellates of Actinobacteria, and high grazing on dominant Burkholderiales taxa. However, there was no consistent “fingerprint” of mixotrophic grazing on prey communities, but the structuring impact rather seemed to depend on the trophic mode of the individual protist taxa, i.e. their dependence on phototrophy vs. phagotrophy. Our findings highlight the differential structuring impact of protist taxa on bacterial communities which may have important ecological implications, for example during periodic dominance of obligate mixotrophic bacterivores in changing lake ecosystems. Nature Publishing Group UK 2023-09-02 /pmc/articles/PMC10475056/ /pubmed/37660188 http://dx.doi.org/10.1038/s43705-023-00289-7 Text en © The Author(s) 2023 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Article
Ivanković, Marina
Ptacnik, Robert
Bengtsson, Mia Maria
Top-down structuring of freshwater bacterial communities by mixotrophic flagellates
title Top-down structuring of freshwater bacterial communities by mixotrophic flagellates
title_full Top-down structuring of freshwater bacterial communities by mixotrophic flagellates
title_fullStr Top-down structuring of freshwater bacterial communities by mixotrophic flagellates
title_full_unstemmed Top-down structuring of freshwater bacterial communities by mixotrophic flagellates
title_short Top-down structuring of freshwater bacterial communities by mixotrophic flagellates
title_sort top-down structuring of freshwater bacterial communities by mixotrophic flagellates
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10475056/
https://www.ncbi.nlm.nih.gov/pubmed/37660188
http://dx.doi.org/10.1038/s43705-023-00289-7
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