Amoebae as Targets for Toxins or Effectors Secreted by Mammalian Pathogens

Samba-Louaka, Ascel

doi:10.3390/toxins13080526

Cited by 5 publications

(2 citation statements)

References 129 publications

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“…The mechanism of bacterial-mediated lysis of protists differs, where some bacteria are reproducing intracellularly (20,21,44,45) and disrupting intracellular components (46) until the protist bursts. In other taxa, lysis occurs through extracellular toxic compounds secreted by the bacteria (10).…”

Section: Virulent Bacteria Display Selective and Density Dependent Ly...mentioning

confidence: 99%

Experimental assessment of marine microbial interactions: from predatory protists promoting bacterial survival to bacterial lysis of the protists

Axelsson-Olsson,

Gubonin,

Israelsson

et al. 2024

Preprint

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Bacteria in aquatic environments are a principal food source for predatory protists. Whereas interactions between bacteria and protists are recognized to play important roles in determining the pathogenesis and epidemiology of several human pathogens, few studies have systematically characterized the interactions between specific aquatic bacteria and protists beyond the prey-predator relation. We therefore surveyed the outcome of individual co-cultures between 18 different genome-sequenced marine bacteria with known virulence gene repertoires and three model protist species widely used for assessing bacteria-protist interactions. Strikingly, ten, five, and three bacterial isolates were capable of lysing the protistsAcanthamoeba polyphaga, Tetrahymena pyriformisandEuglena gracilis, respectively. A majority of the bacteria were able to grow and/or maintain viable populations in the presence of viable protists. Some bacteria survived longer in the presence of viable protists but not heat-killed protists, and were observed in protist vacuoles. In this respect, thus, marine bacteria are similar to several protist-dependent human pathogens, includingLegionella. Analyses of growth patterns in low-nutrient media showed that co-cultivation withA polyphagaallowed one bacterial strain to overcome nutritional stress and obtain active growth. Five isolates depended on viable amoebae to grow, notwithstanding nutrient media status. The remarkable capability of surviving encounters with, and even actively killing, bacterivorous protists, indicates that diverse (and possibly novel) bacterial defense strategies and virulence mechanisms to access nutrients are widespread among marine bacteria. The diversity of interactions uncovered here has important implications for understanding ecological and evolutionary consequences of population dynamics in bacteria and protists.IMPORTANCEThe microbiome constitutes the base of food webs in marine waters. Its composition partly reflects biotic interactions, where bacteria primarily are considered as prey of predatory protists. However, studies that focus on one or a few species have shown that some bacteria have abilities to escape grazing and may even be capable of lysing their protist predators. In this study, we substantially extend these findings by systematically investigating interactions among multiple taxa of both bacteria and protists. Our results show that marine bacteria display a wider and more complex range of interactions with their predators than generally recognized - from growth dependency to protist lysis. Given that such interactions play key roles in the pathogenesis and epidemiology of several human pathogens, our findings imply that bacterial virulence traits can contribute to defining the structure and ecology of the marine microbiome.

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Section: Virulent Bacteria Display Selective and Density Dependent Ly...mentioning

confidence: 99%

Experimental assessment of marine microbial interactions: from predatory protists promoting bacterial survival to bacterial lysis of the protists

Axelsson-Olsson,

Gubonin,

Israelsson

et al. 2024

Preprint

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“…More than a training ground, FLA constitute a natural host and an environmental reservoir that enhances L. pneumophila survival and protection against biocidal treatments, especially in anthropogenic systems like stagnant pipes or cooling towers (Berjeaud et al 2016). Among FLA, Acanthamoeba castellanii is known to be a multiplication site for L. pneumophila and constitutes a good cellular model for Legionella infection (Swart et al 2018;Samba-Louaka 2021). A. castellanii is found in many environments and presents a biphasic life cycle.…”

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confidence: 99%

Proteomic analysis of Acanthamoeba castellanii response to Legionella pneumophila infection

Hay,

Rolland,

Bernard

et al. 2023

FEMS Microbiology Letters

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Legionella pneumophila is an opportunistic pathogen responsible for Legionnaires' disease or Legionellosis. This bacterium is found in the environment interacting with free-living amoebae such as Acanthamoeba castellanii. Until now, proteomic analyses have been done in amoebae infected with L. pneumophila but focused on the Legionella-containing vacuole. In this study, we propose a global proteomic analysis of the A. castellanii proteome following infection with L. pneumophila wild-type (WT) or with an isogenic ΔdotA mutant strain, which is unable to replicate intracellularly. We found that infection with L. pneumophila WT leads to reduced levels of A. castellanii proteins associated with lipid homeostasis/metabolism, GTPase regulation and kinase. The levels of organelle-associated proteins were also decreased during infection. L. pneumophila WT infection leads to increase levels of proteins associated with proteins polyubiquitination, folding or degradation and antioxidant activities. This study reinforces our knowledge of this too-little-explored but so fundamental interaction between L. pneumophila and A. castellanii, to understand how the bacterium could resist amoeba digestion.

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Metagenomics insights into microbiome and antibiotic resistance genes from free living amoeba in chlorinated wastewater effluents

Conco-Biyela,

Malla,

Olatunji Awolusi

et al. 2024

International Journal of Hygiene and Environmental Health

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Amoebae as Targets for Toxins or Effectors Secreted by Mammalian Pathogens

Cited by 5 publications

References 129 publications

Experimental assessment of marine microbial interactions: from predatory protists promoting bacterial survival to bacterial lysis of the protists

Experimental assessment of marine microbial interactions: from predatory protists promoting bacterial survival to bacterial lysis of the protists

Proteomic analysis of Acanthamoeba castellanii response to Legionella pneumophila infection

Metagenomics insights into microbiome and antibiotic resistance genes from free living amoeba in chlorinated wastewater effluents

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