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Paquet VE, Durocher AF, Charette SJ. Aeromonas salmonicida intra-species divergence revealed by the various strategies displayed when grazed by Tetrahymena pyriformis. FEMS Microbiol Lett 2022; 369:6650351. [PMID: 35883218 DOI: 10.1093/femsle/fnac067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 05/31/2022] [Accepted: 07/23/2022] [Indexed: 11/13/2022] Open
Abstract
Worldwide, Aeromonas salmonicida is a major bacterial pathogen of fish in both marine and freshwater environments. Despite psychrophilic growth being common for this species, the number of characterized mesophilic strains is increasing. Thus, this species may serve as a model for the study of intraspecies lifestyle diversity. Although bacteria are preyed upon by protozoan predators, their interaction inside or outside the phagocytic pathway of the predator can provide several advantages to the bacteria. To correlate intraspecies diversity with predation outcome, we studied the fate of psychrophilic and mesophilic strains of A. salmonicida co-cultured with the ciliate Tetrahymena pyriformis. Three types of outcome were observed: digestion, resistance to phagocytosis and pathogenicity. The psychrophilic strains are fully digested by the ciliate. In contrast, the mesophilic A. salmonicida subsp. pectinolytica strain is pathogenic to the ciliate. All the other mesophilic strains display mechanisms to resist phagocytosis and/or digestion, which allow them to survive ciliate predation. In some cases, passage through the phagocytic pathway resulted in a few mesophilic A. salmonicida being packaged inside fecal pellets. This study sheds light on the great phenotypic diversity observed in the complex range of mechanisms used by A. salmonicida to confront a predator.
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Affiliation(s)
- Valérie E Paquet
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada, G1V 0A6.,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada, G1V 0A6.,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (IUCPQ), Quebec City, QC, Canada, G1V 4G5
| | - Alicia F Durocher
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada, G1V 0A6.,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada, G1V 0A6.,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (IUCPQ), Quebec City, QC, Canada, G1V 4G5
| | - Steve J Charette
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, Canada, G1V 0A6.,Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, Canada, G1V 0A6.,Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (IUCPQ), Quebec City, QC, Canada, G1V 4G5
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Amaro F, Martín-González A. Microbial warfare in the wild-the impact of protists on the evolution and virulence of bacterial pathogens. Int Microbiol 2021; 24:559-571. [PMID: 34365574 DOI: 10.1007/s10123-021-00192-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 06/03/2021] [Accepted: 06/28/2021] [Indexed: 01/01/2023]
Abstract
During the long history of co-evolution with protists, bacteria have evolved defense strategies to avoid grazing and survive phagocytosis. These mechanisms allow bacteria to exploit phagocytic cells as a protective niche in which to escape from environmental stress and even replicate. Importantly, these anti-grazing mechanisms can function as virulence factors when bacteria infect humans. Here, we discuss how protozoan predation exerts a selective pressure driving bacterial virulence and shaping their genomes, and how bacteria-protist interactions might contribute to the spread of antibiotic resistance as well. We provide examples to demonstrate that besides being voracious bacterial predators, protozoa can serve as melting pots where intracellular organisms exchange genetic information, or even "training grounds" where some pathogens become hypervirulent after passing through. In this special issue, we would like to emphasize the tremendous impact of bacteria-protist interactions on human health and the potential of amoebae as model systems to study biology and evolution of a variety of pathogens. Besides, a better understanding of bacteria-protist relationships will help us expand our current understanding of bacterial virulence and, likely, how pathogens emerge.
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Affiliation(s)
- Francisco Amaro
- Department of Genetics, Physiology and Microbiology, School of Biology, Complutense University of Madrid, 28040, Madrid, Spain.
| | - Ana Martín-González
- Department of Genetics, Physiology and Microbiology, School of Biology, Complutense University of Madrid, 28040, Madrid, Spain
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