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Quorum Sensing Determines the Choice of Antiphage Defense Strategy in Vibrio anguillarum.

Tan D, Svenningsen SL, Middelboe M - MBio (2015)

Bottom Line: In this study, we found that an important, but so far largely overlooked, determinant of the outcome of phage-bacterial encounters in the fish pathogen Vibrio anguillarum is bacterial cell-cell communication, known as quorum sensing.The phenotypes of the two quorum-sensing mutant strains are accurately reflected in the behavior of wild-type V. anguillarum, which (i) displays increased OmpK expression in aggregated cells compared to free-living variants in the same culture, (ii) displays a clear inverse correlation between ompK mRNA levels and the concentration of N-acylhomoserine lactone quorum-sensing signals in the culture medium, and (iii) survives mainly by one of these two defense mechanisms, rather than by genetic mutation to phage resistance.Taken together, our results demonstrate that V. anguillarum employs quorum-sensing information to choose between two complementary antiphage defense strategies.

View Article: PubMed Central - PubMed

Affiliation: Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark.

No MeSH data available.


Related in: MedlinePlus

(A) Optical densities (OD600) of cultures of V. anguillarum wild-type (wt) and QS mutant (ΔvanT and ΔvanO) strains in the presence or absence of phage KVP40 at an API of 1 were measured at 1-h intervals over a 10-h period of incubation. (B) Corresponding abundances of PFU per milliliter were quantified by plaque assay over a 10-h period of incubation in wild-type + KVP40, ΔvanT + KVP40, and ΔvanO + KVP40 cultures, respectively. Error bars represent standard deviations from all experiments carried out in duplicate.
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fig2: (A) Optical densities (OD600) of cultures of V. anguillarum wild-type (wt) and QS mutant (ΔvanT and ΔvanO) strains in the presence or absence of phage KVP40 at an API of 1 were measured at 1-h intervals over a 10-h period of incubation. (B) Corresponding abundances of PFU per milliliter were quantified by plaque assay over a 10-h period of incubation in wild-type + KVP40, ΔvanT + KVP40, and ΔvanO + KVP40 cultures, respectively. Error bars represent standard deviations from all experiments carried out in duplicate.

Mentions: Further assessments of QS-mediated regulation of phage infectivity in 10-h-infection experiments with phage KVP40 and three hosts (wild-type, ΔvanT, and ΔvanO strains) showed strong effects of the mutational changes on phage-host interactions. Phage KVP40 reduced cell density in the wild-type and ΔvanT cultures within the 10-h incubation by 60% and 75%, respectively, relative to the optical density (OD) of control cultures without phages, with significantly lower OD values in the ΔvanT culture than in the wild-type culture (0.62 and 0.88 after 10 h, respectively) (Fig. 2A). In the ΔvanO culture, on the other hand, OD was not significantly affected by phage addition (Fig. 2A). In accordance with these results, we observed rapid phage propagation in the wild-type and ΔvanT cultures where KVP40 abundance stabilized at ~1010 PFU ml−1, whereas the phage production was ~100-fold lower in the ΔvanO culture (Fig. 2B). We note that the minimum OD values of 0.33 and 0.15 after 5 h in the phage-treated wild-type and ΔvanT cultures, respectively, were followed by a regrowth of cells during the remainder of the incubation (Fig. 2A), despite the abundance of KVP40 phage.


Quorum Sensing Determines the Choice of Antiphage Defense Strategy in Vibrio anguillarum.

Tan D, Svenningsen SL, Middelboe M - MBio (2015)

(A) Optical densities (OD600) of cultures of V. anguillarum wild-type (wt) and QS mutant (ΔvanT and ΔvanO) strains in the presence or absence of phage KVP40 at an API of 1 were measured at 1-h intervals over a 10-h period of incubation. (B) Corresponding abundances of PFU per milliliter were quantified by plaque assay over a 10-h period of incubation in wild-type + KVP40, ΔvanT + KVP40, and ΔvanO + KVP40 cultures, respectively. Error bars represent standard deviations from all experiments carried out in duplicate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4471561&req=5

fig2: (A) Optical densities (OD600) of cultures of V. anguillarum wild-type (wt) and QS mutant (ΔvanT and ΔvanO) strains in the presence or absence of phage KVP40 at an API of 1 were measured at 1-h intervals over a 10-h period of incubation. (B) Corresponding abundances of PFU per milliliter were quantified by plaque assay over a 10-h period of incubation in wild-type + KVP40, ΔvanT + KVP40, and ΔvanO + KVP40 cultures, respectively. Error bars represent standard deviations from all experiments carried out in duplicate.
Mentions: Further assessments of QS-mediated regulation of phage infectivity in 10-h-infection experiments with phage KVP40 and three hosts (wild-type, ΔvanT, and ΔvanO strains) showed strong effects of the mutational changes on phage-host interactions. Phage KVP40 reduced cell density in the wild-type and ΔvanT cultures within the 10-h incubation by 60% and 75%, respectively, relative to the optical density (OD) of control cultures without phages, with significantly lower OD values in the ΔvanT culture than in the wild-type culture (0.62 and 0.88 after 10 h, respectively) (Fig. 2A). In the ΔvanO culture, on the other hand, OD was not significantly affected by phage addition (Fig. 2A). In accordance with these results, we observed rapid phage propagation in the wild-type and ΔvanT cultures where KVP40 abundance stabilized at ~1010 PFU ml−1, whereas the phage production was ~100-fold lower in the ΔvanO culture (Fig. 2B). We note that the minimum OD values of 0.33 and 0.15 after 5 h in the phage-treated wild-type and ΔvanT cultures, respectively, were followed by a regrowth of cells during the remainder of the incubation (Fig. 2A), despite the abundance of KVP40 phage.

Bottom Line: In this study, we found that an important, but so far largely overlooked, determinant of the outcome of phage-bacterial encounters in the fish pathogen Vibrio anguillarum is bacterial cell-cell communication, known as quorum sensing.The phenotypes of the two quorum-sensing mutant strains are accurately reflected in the behavior of wild-type V. anguillarum, which (i) displays increased OmpK expression in aggregated cells compared to free-living variants in the same culture, (ii) displays a clear inverse correlation between ompK mRNA levels and the concentration of N-acylhomoserine lactone quorum-sensing signals in the culture medium, and (iii) survives mainly by one of these two defense mechanisms, rather than by genetic mutation to phage resistance.Taken together, our results demonstrate that V. anguillarum employs quorum-sensing information to choose between two complementary antiphage defense strategies.

View Article: PubMed Central - PubMed

Affiliation: Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark.

No MeSH data available.


Related in: MedlinePlus