ORCID

Abstract

Summary.Diatoms are globally abundant microalgae that form extensive blooms in aquatic ecosystems. Certain bacteria behave antagonistically towards diatoms, killing or inhibiting their growth. Despite their crucial implications to diatom bloom and population health, knowledge of diatom antagonists in the environment is fundamentally lacking. We report systematic characterisation of the diversity and seasonal dynamics of bacterial antagonists of diatoms via plaque assay sampling in the Western English Channel, where diatoms frequently bloom. Unexpectedly, peaks in detection did not occur during characteristic spring diatom blooms, but coincided with a winter bloom of Coscinodiscus, suggesting that these bacteria likely influence distinct diatom host populations. We isolated multiple bacterial antagonists, spanning 4 classes and 10 bacterial orders. Notably, a diatom attaching Roseobacter Ponticoccus alexandriiwas isolated multiple times, indicative of a persistent environmental presence. Moreover, many isolates had no prior reports of antagonistic activity towards diatoms. We verified diatom growth inhibitory effects of eight isolates. In all cases tested, these effects were activated by pre-exposure to diatom organic matter. Discovery of widespread ‘cryptic’ antagonistic activity indicates that bacterial pathogenicity towards diatoms is more prevalent than previously recognised. Finally, examination of the global biogeography of WEC antagonists revealed co-occurrence patterns with diatom host populations in marine waters globally.

Publication Date

2024-02-01

Publication Title

New Phytologist

Volume

241

Issue

3

ISSN

0028-646X

Acceptance Date

2023-10-27

Deposit Date

2023-12-18

Embargo Period

2023-12-19

Funding

We acknowledge support from the NERC Independent Research Fellowship grant NE/R015449/2 (KEH) and PhD studentship from the NERC ARIES doctoral training programme NE/ S007334/1 (LB). CEW was supported by funding from the NERC National Capability Long-term Single Centre Science Programme, Climate Linked Atlantic Sector Science, grant no. NE/R015953/1. We also thank the crew of the research vessel Sepia (MBA, Plymouth, UK) for their collection of samples used during this study.

Keywords

algicidal, Coscinodiscus, diatom–bacteria interactions, diatoms, plaque assay, Ponticoccus

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

First Page

1292

Last Page

1307

Download

Share

COinS