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Response to Gaseous NO2 Air Pollutant of P. fluorescens Airborne Strain MFAF76a and Clinical Strain MFN1032.

Kondakova T, Catovic C, Barreau M, Nusser M, Brenner-Weiss G, Chevalier S, Dionnet F, Orange N, Poc CD - Front Microbiol (2016)

Bottom Line: Human exposure to nitrogen dioxide (NO2), an air pollutant of increasing interest in biology, results in several toxic effects to human health and also to the air microbiota.Finally, NO2-exposed P. fluorescens strains were found to be more resistant to ciprofloxacin and chloramphenicol.Taken together, our study provides evidences for the bacterial response to NO2 toxicity.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Microbiology Signals and Microenvironment EA 4312, Normandy University, University of Rouen, SéSa, IRIBEvreux, France; Aerothermic and Internal Combustion Engine Technological Research CentreSaint Etienne du Rouvray, France.

ABSTRACT
Human exposure to nitrogen dioxide (NO2), an air pollutant of increasing interest in biology, results in several toxic effects to human health and also to the air microbiota. The aim of this study was to investigate the bacterial response to gaseous NO2. Two Pseudomonas fluorescens strains, namely the airborne strain MFAF76a and the clinical strain MFN1032 were exposed to 0.1, 5, or 45 ppm concentrations of NO2, and their effects on bacteria were evaluated in terms of motility, biofilm formation, antibiotic resistance, as well as expression of several chosen target genes. While 0.1 and 5 ppm of NO2did not lead to any detectable modification in the studied phenotypes of the two bacteria, several alterations were observed when the bacteria were exposed to 45 ppm of gaseous NO2. We thus chose to focus on this high concentration. NO2-exposed P. fluorescens strains showed reduced swimming motility, and decreased swarming in case of the strain MFN1032. Biofilm formed by NO2-treated airborne strain MFAF76a showed increased maximum thickness compared to non-treated cells, while NO2 had no apparent effect on the clinical MFN1032 biofilm structure. It is well known that biofilm and motility are inversely regulated by intracellular c-di-GMP level. The c-di-GMP level was however not affected in response to NO2 treatment. Finally, NO2-exposed P. fluorescens strains were found to be more resistant to ciprofloxacin and chloramphenicol. Accordingly, the resistance nodulation cell division (RND) MexEF-OprN efflux pump encoding genes were highly upregulated in the two P. fluorescens strains. Noticeably, similar phenotypes had been previously observed following a NO treatment. Interestingly, an hmp-homolog gene in P. fluorescens strains MFAF76a and MFN1032 encodes a NO dioxygenase that is involved in NO detoxification into nitrites. Its expression was upregulated in response to NO2, suggesting a possible common pathway between NO and NO2 detoxification. Taken together, our study provides evidences for the bacterial response to NO2 toxicity.

No MeSH data available.


Related in: MedlinePlus

NO2 decreases P. fluorescens motility. Airborne MFAF76a and clinical MFN1032 P. fluorescens strains were exposed in triplicate to 45 ppm of NO2(). Swimming (A) and swarming (B) motilities were assayed on DMB-swim/swarm plates after 24 h incubation. The motile bacterial movement was evaluated in three independent experiments with three replicates. The data were compared with control exposed to synthetic air (). Obtained results are presented as average values ± SEM. Statistical significance was calculated by the non-parametric Mann-Whitney-Test p < 0.05 (*) and < 0.001 (***).
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Figure 3: NO2 decreases P. fluorescens motility. Airborne MFAF76a and clinical MFN1032 P. fluorescens strains were exposed in triplicate to 45 ppm of NO2(). Swimming (A) and swarming (B) motilities were assayed on DMB-swim/swarm plates after 24 h incubation. The motile bacterial movement was evaluated in three independent experiments with three replicates. The data were compared with control exposed to synthetic air (). Obtained results are presented as average values ± SEM. Statistical significance was calculated by the non-parametric Mann-Whitney-Test p < 0.05 (*) and < 0.001 (***).

Mentions: Swimming concerns motility in a liquid medium, mediated by production and activity of flagella. As shown on Figure 3A, gaseous NO2 exposition significantly decreased the swimming motility of both strains, suggesting an impairment of the flagellum production and/or activity.


Response to Gaseous NO2 Air Pollutant of P. fluorescens Airborne Strain MFAF76a and Clinical Strain MFN1032.

Kondakova T, Catovic C, Barreau M, Nusser M, Brenner-Weiss G, Chevalier S, Dionnet F, Orange N, Poc CD - Front Microbiol (2016)

NO2 decreases P. fluorescens motility. Airborne MFAF76a and clinical MFN1032 P. fluorescens strains were exposed in triplicate to 45 ppm of NO2(). Swimming (A) and swarming (B) motilities were assayed on DMB-swim/swarm plates after 24 h incubation. The motile bacterial movement was evaluated in three independent experiments with three replicates. The data were compared with control exposed to synthetic air (). Obtained results are presented as average values ± SEM. Statistical significance was calculated by the non-parametric Mann-Whitney-Test p < 0.05 (*) and < 0.001 (***).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814523&req=5

Figure 3: NO2 decreases P. fluorescens motility. Airborne MFAF76a and clinical MFN1032 P. fluorescens strains were exposed in triplicate to 45 ppm of NO2(). Swimming (A) and swarming (B) motilities were assayed on DMB-swim/swarm plates after 24 h incubation. The motile bacterial movement was evaluated in three independent experiments with three replicates. The data were compared with control exposed to synthetic air (). Obtained results are presented as average values ± SEM. Statistical significance was calculated by the non-parametric Mann-Whitney-Test p < 0.05 (*) and < 0.001 (***).
Mentions: Swimming concerns motility in a liquid medium, mediated by production and activity of flagella. As shown on Figure 3A, gaseous NO2 exposition significantly decreased the swimming motility of both strains, suggesting an impairment of the flagellum production and/or activity.

Bottom Line: Human exposure to nitrogen dioxide (NO2), an air pollutant of increasing interest in biology, results in several toxic effects to human health and also to the air microbiota.Finally, NO2-exposed P. fluorescens strains were found to be more resistant to ciprofloxacin and chloramphenicol.Taken together, our study provides evidences for the bacterial response to NO2 toxicity.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Microbiology Signals and Microenvironment EA 4312, Normandy University, University of Rouen, SéSa, IRIBEvreux, France; Aerothermic and Internal Combustion Engine Technological Research CentreSaint Etienne du Rouvray, France.

ABSTRACT
Human exposure to nitrogen dioxide (NO2), an air pollutant of increasing interest in biology, results in several toxic effects to human health and also to the air microbiota. The aim of this study was to investigate the bacterial response to gaseous NO2. Two Pseudomonas fluorescens strains, namely the airborne strain MFAF76a and the clinical strain MFN1032 were exposed to 0.1, 5, or 45 ppm concentrations of NO2, and their effects on bacteria were evaluated in terms of motility, biofilm formation, antibiotic resistance, as well as expression of several chosen target genes. While 0.1 and 5 ppm of NO2did not lead to any detectable modification in the studied phenotypes of the two bacteria, several alterations were observed when the bacteria were exposed to 45 ppm of gaseous NO2. We thus chose to focus on this high concentration. NO2-exposed P. fluorescens strains showed reduced swimming motility, and decreased swarming in case of the strain MFN1032. Biofilm formed by NO2-treated airborne strain MFAF76a showed increased maximum thickness compared to non-treated cells, while NO2 had no apparent effect on the clinical MFN1032 biofilm structure. It is well known that biofilm and motility are inversely regulated by intracellular c-di-GMP level. The c-di-GMP level was however not affected in response to NO2 treatment. Finally, NO2-exposed P. fluorescens strains were found to be more resistant to ciprofloxacin and chloramphenicol. Accordingly, the resistance nodulation cell division (RND) MexEF-OprN efflux pump encoding genes were highly upregulated in the two P. fluorescens strains. Noticeably, similar phenotypes had been previously observed following a NO treatment. Interestingly, an hmp-homolog gene in P. fluorescens strains MFAF76a and MFN1032 encodes a NO dioxygenase that is involved in NO detoxification into nitrites. Its expression was upregulated in response to NO2, suggesting a possible common pathway between NO and NO2 detoxification. Taken together, our study provides evidences for the bacterial response to NO2 toxicity.

No MeSH data available.


Related in: MedlinePlus