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The Agr communication system provides a benefit to the populations of Listeria monocytogenes in soil.

Vivant AL, Garmyn D, Gal L, Piveteau P - Front Cell Infect Microbiol (2014)

Bottom Line: Alteration of the ability to communicate, either by deletion of the gene coding the response regulator AgrA (response-negative mutant) or the signal pro-peptide AgrD (signal-negative mutant), did not affect population dynamics in soil that had been sterilized but survival was altered in biotic soil suggesting that the Agr system of L. monocytogenes was involved to face the complex soil biotic environment.These results showed that the ability to respond to Agr communication provided a benefit to listerial cells to compete.These results might also indicate that in soil, the Agr system controls private goods rather than public goods.

View Article: PubMed Central - PubMed

Affiliation: Unités Mixtes de Recherche1347 Agroécologie, Université de Bourgogne Dijon, France ; Institut National de la Recherche Agronomique, Unités Mixtes de Recherche1347 Agroécologie Dijon, France.

ABSTRACT
In this study, we investigated whether the Agr communication system of the pathogenic bacterium Listeria monocytogenes was involved in adaptation and competitiveness in soil. Alteration of the ability to communicate, either by deletion of the gene coding the response regulator AgrA (response-negative mutant) or the signal pro-peptide AgrD (signal-negative mutant), did not affect population dynamics in soil that had been sterilized but survival was altered in biotic soil suggesting that the Agr system of L. monocytogenes was involved to face the complex soil biotic environment. This was confirmed by a set of co-incubation experiments. The fitness of the response-negative mutant was lower either in the presence or absence of the parental strain but the fitness of the signal-negative mutant depended on the strain with which it was co-incubated. The survival of the signal-negative mutant was higher when co-cultured with the parental strain than when co-cultured with the response-negative mutant. These results showed that the ability to respond to Agr communication provided a benefit to listerial cells to compete. These results might also indicate that in soil, the Agr system controls private goods rather than public goods.

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Dynamics of (A) the parental strain, (B) the response-negative mutant and (C) the signal-negative mutant populations in biotic soil microcosms. (♦) Single culture, () co-culture with the parental strain, () co-culture with the response-negative mutant, () co-culture with the signal-negative mutant. Error bars represent the standard deviation from three replicate samples value.
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Figure 4: Dynamics of (A) the parental strain, (B) the response-negative mutant and (C) the signal-negative mutant populations in biotic soil microcosms. (♦) Single culture, () co-culture with the parental strain, () co-culture with the response-negative mutant, () co-culture with the signal-negative mutant. Error bars represent the standard deviation from three replicate samples value.

Mentions: Under biotic conditions, survival of the parental strain (Figure 4A) and the response-negative mutant (Figure 4B) did not vary whatever the co-culture tested. On the opposite, results indicated a significant (ANOVA, P < 0.05) improvement of the signal-negative mutant's survival when co-cultured with the parental strain but not when co-cultured with the response-negative mutant (Figure 4C). This indicates that the fitness of the signal-mute strain depended of the presence or absence of cells with active Agr systems and that the parental strain provided a benefit to this mutant. In addition to this, CI measurements showed that under biotic conditions, the CI of the response-negative mutant co-incubated with the parental strain significantly (ANOVA, P < 0.05) decreased over time (Table 3). Under these conditions, the parental strain had a significant competitive advantage over the response-negative mutant. The inability to respond to Agr communication was detrimental to the survival of the response-negative mutant. This is supporting the idea that the Agr communication system is important for competitiveness of L. monocytogenes in soil when complex microbial communities are active. When the signal-negative mutant and the parental strain were co-inoculated, the analysis of variance showed that the CI did not significantly vary over the 14 days of the experiment except after 2 days of incubation where the CI of the signal-negative mutant was significantly lower than the parental strain (P < 0.05) (Table 3). These results suggest that, at later stages of incubation, the fitness of the signal-negative mutant was similar to the fitness of the parental strain during co-culture, confirming that the presence of the parental strain improved competitiveness of the signal-negative mutant. Finally, when the two mutants were tested in biotic soil microcosms, the CI did not vary significantly over time (Table 3) meaning that none of the mutants took advantage over the other during the 14 days of incubation.


The Agr communication system provides a benefit to the populations of Listeria monocytogenes in soil.

Vivant AL, Garmyn D, Gal L, Piveteau P - Front Cell Infect Microbiol (2014)

Dynamics of (A) the parental strain, (B) the response-negative mutant and (C) the signal-negative mutant populations in biotic soil microcosms. (♦) Single culture, () co-culture with the parental strain, () co-culture with the response-negative mutant, () co-culture with the signal-negative mutant. Error bars represent the standard deviation from three replicate samples value.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4222237&req=5

Figure 4: Dynamics of (A) the parental strain, (B) the response-negative mutant and (C) the signal-negative mutant populations in biotic soil microcosms. (♦) Single culture, () co-culture with the parental strain, () co-culture with the response-negative mutant, () co-culture with the signal-negative mutant. Error bars represent the standard deviation from three replicate samples value.
Mentions: Under biotic conditions, survival of the parental strain (Figure 4A) and the response-negative mutant (Figure 4B) did not vary whatever the co-culture tested. On the opposite, results indicated a significant (ANOVA, P < 0.05) improvement of the signal-negative mutant's survival when co-cultured with the parental strain but not when co-cultured with the response-negative mutant (Figure 4C). This indicates that the fitness of the signal-mute strain depended of the presence or absence of cells with active Agr systems and that the parental strain provided a benefit to this mutant. In addition to this, CI measurements showed that under biotic conditions, the CI of the response-negative mutant co-incubated with the parental strain significantly (ANOVA, P < 0.05) decreased over time (Table 3). Under these conditions, the parental strain had a significant competitive advantage over the response-negative mutant. The inability to respond to Agr communication was detrimental to the survival of the response-negative mutant. This is supporting the idea that the Agr communication system is important for competitiveness of L. monocytogenes in soil when complex microbial communities are active. When the signal-negative mutant and the parental strain were co-inoculated, the analysis of variance showed that the CI did not significantly vary over the 14 days of the experiment except after 2 days of incubation where the CI of the signal-negative mutant was significantly lower than the parental strain (P < 0.05) (Table 3). These results suggest that, at later stages of incubation, the fitness of the signal-negative mutant was similar to the fitness of the parental strain during co-culture, confirming that the presence of the parental strain improved competitiveness of the signal-negative mutant. Finally, when the two mutants were tested in biotic soil microcosms, the CI did not vary significantly over time (Table 3) meaning that none of the mutants took advantage over the other during the 14 days of incubation.

Bottom Line: Alteration of the ability to communicate, either by deletion of the gene coding the response regulator AgrA (response-negative mutant) or the signal pro-peptide AgrD (signal-negative mutant), did not affect population dynamics in soil that had been sterilized but survival was altered in biotic soil suggesting that the Agr system of L. monocytogenes was involved to face the complex soil biotic environment.These results showed that the ability to respond to Agr communication provided a benefit to listerial cells to compete.These results might also indicate that in soil, the Agr system controls private goods rather than public goods.

View Article: PubMed Central - PubMed

Affiliation: Unités Mixtes de Recherche1347 Agroécologie, Université de Bourgogne Dijon, France ; Institut National de la Recherche Agronomique, Unités Mixtes de Recherche1347 Agroécologie Dijon, France.

ABSTRACT
In this study, we investigated whether the Agr communication system of the pathogenic bacterium Listeria monocytogenes was involved in adaptation and competitiveness in soil. Alteration of the ability to communicate, either by deletion of the gene coding the response regulator AgrA (response-negative mutant) or the signal pro-peptide AgrD (signal-negative mutant), did not affect population dynamics in soil that had been sterilized but survival was altered in biotic soil suggesting that the Agr system of L. monocytogenes was involved to face the complex soil biotic environment. This was confirmed by a set of co-incubation experiments. The fitness of the response-negative mutant was lower either in the presence or absence of the parental strain but the fitness of the signal-negative mutant depended on the strain with which it was co-incubated. The survival of the signal-negative mutant was higher when co-cultured with the parental strain than when co-cultured with the response-negative mutant. These results showed that the ability to respond to Agr communication provided a benefit to listerial cells to compete. These results might also indicate that in soil, the Agr system controls private goods rather than public goods.

Show MeSH
Related in: MedlinePlus