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Escherichia coli Strains Display Varying Susceptibility to Grazing by the Soil Amoeba Dictyostelium discoideum

Recent studies have shown that Escherichia coli can survive in different environments, including soils, and they can maintain populations in sterile soil for a long period of time. This indicates that growth-supporting nutrients are available; however, when grown in non-sterile soils, populations de...

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Autores principales: NandaKafle, Gitanjali, Blasius, Lane A., Seale, Tarren, Brözel, Volker S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10304320/
https://www.ncbi.nlm.nih.gov/pubmed/37374960
http://dx.doi.org/10.3390/microorganisms11061457
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author NandaKafle, Gitanjali
Blasius, Lane A.
Seale, Tarren
Brözel, Volker S.
author_facet NandaKafle, Gitanjali
Blasius, Lane A.
Seale, Tarren
Brözel, Volker S.
author_sort NandaKafle, Gitanjali
collection PubMed
description Recent studies have shown that Escherichia coli can survive in different environments, including soils, and they can maintain populations in sterile soil for a long period of time. This indicates that growth-supporting nutrients are available; however, when grown in non-sterile soils, populations decline, suggesting that other biological factors play a role in controlling E. coli populations in soil. Free-living protozoa can affect the bacterial population by grazing. We hypothesized that E. coli strains capable of surviving in non-sterile soil possess mechanisms to protect themselves from amoeba predation. We determined the grazing rate of E. coli pasture isolates by using Dictyostelium discoideum. Bacterial suspensions applied to lactose agar as lines were allowed to grow for 24 h, when 4 μL of D. discoideum culture was inoculated in the center of each bacterial line. Grazing distances were measured after 4 days. The genomes of five grazing-susceptible and five grazing-resistant isolates were sequenced and compared. Grazing distance varied among isolates, which indicated that some E. coli are more susceptible to grazing by protozoa than others. When presented with a choice between grazing-susceptible and grazing-resistant isolates, D. discoideum grazed only on the susceptible strain. Grazing susceptibility phenotype did not align with the phylogroup, with both B1 and E strains found in both grazing groups. They also did not align by core genome phylogeny. Whole genome comparisons revealed that the five most highly grazed strains had 389 shared genes not found in the five least grazed strains. Conversely, the five least grazed strains shared 130 unique genes. The results indicate that long-term persistence of E. coli in soil is due at least in part to resistance to grazing by soil amoeba.
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spelling pubmed-103043202023-06-29 Escherichia coli Strains Display Varying Susceptibility to Grazing by the Soil Amoeba Dictyostelium discoideum NandaKafle, Gitanjali Blasius, Lane A. Seale, Tarren Brözel, Volker S. Microorganisms Article Recent studies have shown that Escherichia coli can survive in different environments, including soils, and they can maintain populations in sterile soil for a long period of time. This indicates that growth-supporting nutrients are available; however, when grown in non-sterile soils, populations decline, suggesting that other biological factors play a role in controlling E. coli populations in soil. Free-living protozoa can affect the bacterial population by grazing. We hypothesized that E. coli strains capable of surviving in non-sterile soil possess mechanisms to protect themselves from amoeba predation. We determined the grazing rate of E. coli pasture isolates by using Dictyostelium discoideum. Bacterial suspensions applied to lactose agar as lines were allowed to grow for 24 h, when 4 μL of D. discoideum culture was inoculated in the center of each bacterial line. Grazing distances were measured after 4 days. The genomes of five grazing-susceptible and five grazing-resistant isolates were sequenced and compared. Grazing distance varied among isolates, which indicated that some E. coli are more susceptible to grazing by protozoa than others. When presented with a choice between grazing-susceptible and grazing-resistant isolates, D. discoideum grazed only on the susceptible strain. Grazing susceptibility phenotype did not align with the phylogroup, with both B1 and E strains found in both grazing groups. They also did not align by core genome phylogeny. Whole genome comparisons revealed that the five most highly grazed strains had 389 shared genes not found in the five least grazed strains. Conversely, the five least grazed strains shared 130 unique genes. The results indicate that long-term persistence of E. coli in soil is due at least in part to resistance to grazing by soil amoeba. MDPI 2023-05-31 /pmc/articles/PMC10304320/ /pubmed/37374960 http://dx.doi.org/10.3390/microorganisms11061457 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
NandaKafle, Gitanjali
Blasius, Lane A.
Seale, Tarren
Brözel, Volker S.
Escherichia coli Strains Display Varying Susceptibility to Grazing by the Soil Amoeba Dictyostelium discoideum
title Escherichia coli Strains Display Varying Susceptibility to Grazing by the Soil Amoeba Dictyostelium discoideum
title_full Escherichia coli Strains Display Varying Susceptibility to Grazing by the Soil Amoeba Dictyostelium discoideum
title_fullStr Escherichia coli Strains Display Varying Susceptibility to Grazing by the Soil Amoeba Dictyostelium discoideum
title_full_unstemmed Escherichia coli Strains Display Varying Susceptibility to Grazing by the Soil Amoeba Dictyostelium discoideum
title_short Escherichia coli Strains Display Varying Susceptibility to Grazing by the Soil Amoeba Dictyostelium discoideum
title_sort escherichia coli strains display varying susceptibility to grazing by the soil amoeba dictyostelium discoideum
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10304320/
https://www.ncbi.nlm.nih.gov/pubmed/37374960
http://dx.doi.org/10.3390/microorganisms11061457
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