Microbial Grazers May Aid in Controlling Infections Caused by the Aquatic Zoosporic Fungus <i>Batrachochytrium dendrobatidis</i>


Farthing, Hazel N, Jiang, Jiamei, Henwood, Alexandra J, Fenton, Andy ORCID: 0000-0002-7676-917X, Garner, Trent WJ, Daversa, David R, Fisher, Matthew C and Montagnes, David JS ORCID: 0000-0001-8826-9837 (2021) Microbial Grazers May Aid in Controlling Infections Caused by the Aquatic Zoosporic Fungus <i>Batrachochytrium dendrobatidis</i>. FRONTIERS IN MICROBIOLOGY, 11. 592286-.

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Abstract

Free-living eukaryotic microbes may reduce animal diseases. We evaluated the dynamics by which micrograzers (primarily protozoa) apply top-down control on the chytrid <i>Batrachochytrium dendrobatidis</i> (<i>Bd</i>) a devastating, panzootic pathogen of amphibians. Although micrograzers consumed zoospores (∼3 μm), the dispersal stage of chytrids, not all species grew monoxenically on zoospores. However, the ubiquitous ciliate <i>Tetrahymena pyriformis</i>, which likely co-occurs with <i>Bd</i>, grew at near its maximum rate (<i>r</i> = 1.7 d<sup>-1</sup>). A functional response (ingestion vs. prey abundance) for <i>T. pyriformis</i>, measured using spore-surrogates (microspheres) revealed maximum ingestion (<i>I</i> <sub><i>max</i></sub> ) of 1.63 × 10<sup>3</sup> zoospores d<sup>-1</sup>, with a half saturation constant (<i>k</i>) of 5.75 × 10<sup>3</sup> zoospores ml<sup>-1</sup>. Using these growth and grazing data we developed and assessed a population model that incorporated chytrid-host and micrograzer dynamics. Simulations using our data and realistic parameters obtained from the literature suggested that micrograzers could control <i>Bd</i> and potentially prevent chytridiomycosis (defined as 10<sup>4</sup> sporangia host<sup>-1</sup>). However, simulated inferior micrograzers (0.7 × <i>I</i> <sub><i>max</i></sub> and 1.5 × <i>k</i>) did not prevent chytridiomycosis, although they ultimately reduced pathogen abundance to below levels resulting in disease. These findings indicate how micrograzer responses can be applied when modeling disease dynamics for <i>Bd</i> and other zoosporic fungi.

Item Type: Article
Uncontrolled Keywords: ciliates, disease, fungi, microbial loop, protozoa, Tetrahymena
Depositing User: Symplectic Admin
Date Deposited: 12 Jan 2021 11:29
Last Modified: 07 Oct 2023 06:19
DOI: 10.3389/fmicb.2020.592286
Open Access URL: https://doi.org/10.3389/fmicb.2020.592286
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3110805
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