A1 Journal article (refereed)
Nutrient enrichment increases virulence in an opportunistic environmental pathogen, with greater effect at low bacterial doses (2024)

Pulkkinen, K., & Taskinen, J. (2024). Nutrient enrichment increases virulence in an opportunistic environmental pathogen, with greater effect at low bacterial doses. FEMS Microbiology Ecology, 100(4), Article fiae013. https://doi.org/10.1093/femsec/fiae013

JYU authors or editors

Publication details

All authors or editors: Pulkkinen, Katja; Taskinen, Jouni

Journal or series: FEMS Microbiology Ecology

ISSN: 0168-6496

eISSN: 1574-6941

Publication year: 2024

Publication date: 01/02/2024

Volume: 100

Issue number: 4

Article number: fiae013

Publisher: Oxford University Press (OUP)

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1093/femsec/fiae013

Publication open access: Openly available

Publication channel open access: Partially open access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/94379

Abstract

Eutrophication of aquatic ecosystems is associated with an increased risk of pathogen infection via increased pathogen growth and host exposure via increased pathogen doses. Here we studied the effect of nutrients on the virulence of an opportunistic bacterial pathogen of fish, Flavobacterium columnare, in challenge experiments with rainbow trout fingerlings. We hypothesized that removing all nutrients by washing the bacteria would reduce virulence as compared to unwashed bacteria, but adding nutrients to the tank water would increase the virulence of the bacterium. Nutrient addition and increase in bacterial dose increased virulence for both unwashed and washed bacteria. For unwashed bacteria, the addition of nutrients reduced the survival probability of fish challenged with low bacterial doses more than for fish challenged with higher bacterial doses, suggesting activation of bacterial virulence factors. Washing and centrifugation reduced viable bacterial counts, and the addition of washed bacteria alone did not lead to fish mortality. However, a small addition of nutrient medium, 0.05% of the total water volume, added separately to the fish container, restored the virulence of the washed bacteria. Our results show that human-induced eutrophication could trigger epidemics of aquatic pathogens at the limits of their survival and affect their ecology and evolution by altering the dynamics between strains that differ in their growth characteristics.

Keywords: fishes; fish diseases; bacteria; eutrophication; pathogens

Free keywords: aquatic environment; bacterium; eutrophication; fish disease; Flavobacterium columnare; nutrient

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