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Escherichia coli morphological changes and lipid A removal induced by reduced pressure nitrogen afterglow exposure.

Zerrouki H, Rizzati V, Bernis C, Nègre-Salvayre A, Sarrette JP, Cousty S - PLoS ONE (2015)

Bottom Line: Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr) can be used for the sterilization of surfaces and of the reusable medical instrumentation.In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow.The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted) lipid A.

View Article: PubMed Central - PubMed

Affiliation: Université de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d'Energie), Bât. 3R2, F-31062, Toulouse, France; CNRS, LAPLACE, F-31062 Toulouse, France.

ABSTRACT
Lipid A is a major hydrophobic component of lipopolysaccharides (endotoxin) present in the membrane of most Gram-negative bacteria, and the major responsible for the bioactivity and toxicity of the endotoxin. Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr) can be used for the sterilization of surfaces and of the reusable medical instrumentation. In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow. In parallel, the time variation of the inactivation efficiency quantified by the log reduction of the initial Escherichia coli (E. coli) population is correlated with morphologic changes observed on the bacteria by scanning electron microscopy (SEM) for increasing afterglow exposure times. The effect of the afterglow exposure is also studied on pure lipid A and on lipid A extracted from exposed E. coli bacteria. We report that more than 60% of lipid A (pure or bacteria-extracted) are lost with the used operating conditions (nitrogen flow QN2 = 1 standard liter per minute (slpm), pressure p = 5 Torr, microwave injected power PMW = 200 W, exposure time: 40 minutes). The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted) lipid A. Altogether these results point out the ability of reduced pressure nitrogen afterglows to neutralize the cytotoxic components in Gram-negative bacteria.

No MeSH data available.


Related in: MedlinePlus

Flowing afterglow set up.
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pone.0116083.g001: Flowing afterglow set up.

Mentions: The used afterglow set up is presented in Fig. 1. It is composed of a surfatron cavity excited by a Sairem GMP 03 KE/D microwave generator operating at 2.45 GHz and producing a discharge in a quartz tube of internal diameter 4 mm at a power PMW varying between 50 and 300 W. The N2 flow rate QN2 is controlled by SLA 5850S Brooks flow-meters in the range between 1.0 and 3.0 slpm while the gas pressure p in the 5 litre cylindrical Pyrex reactor can be tuned between 4 and 30 Torr by means of a throttle valve. The 4 mm i.d. discharge tube enlarges to 19 mm before a bent and is connected by a Teflon junction to a Pyrex tube of identical diameter (19 mm) before the entrance of a 5 litre reactor where samples can be exposed to the afterglow flow. The total distance d between the surfatron and the reactor is set to 56 cm.


Escherichia coli morphological changes and lipid A removal induced by reduced pressure nitrogen afterglow exposure.

Zerrouki H, Rizzati V, Bernis C, Nègre-Salvayre A, Sarrette JP, Cousty S - PLoS ONE (2015)

Flowing afterglow set up.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383372&req=5

pone.0116083.g001: Flowing afterglow set up.
Mentions: The used afterglow set up is presented in Fig. 1. It is composed of a surfatron cavity excited by a Sairem GMP 03 KE/D microwave generator operating at 2.45 GHz and producing a discharge in a quartz tube of internal diameter 4 mm at a power PMW varying between 50 and 300 W. The N2 flow rate QN2 is controlled by SLA 5850S Brooks flow-meters in the range between 1.0 and 3.0 slpm while the gas pressure p in the 5 litre cylindrical Pyrex reactor can be tuned between 4 and 30 Torr by means of a throttle valve. The 4 mm i.d. discharge tube enlarges to 19 mm before a bent and is connected by a Teflon junction to a Pyrex tube of identical diameter (19 mm) before the entrance of a 5 litre reactor where samples can be exposed to the afterglow flow. The total distance d between the surfatron and the reactor is set to 56 cm.

Bottom Line: Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr) can be used for the sterilization of surfaces and of the reusable medical instrumentation.In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow.The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted) lipid A.

View Article: PubMed Central - PubMed

Affiliation: Université de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d'Energie), Bât. 3R2, F-31062, Toulouse, France; CNRS, LAPLACE, F-31062 Toulouse, France.

ABSTRACT
Lipid A is a major hydrophobic component of lipopolysaccharides (endotoxin) present in the membrane of most Gram-negative bacteria, and the major responsible for the bioactivity and toxicity of the endotoxin. Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr) can be used for the sterilization of surfaces and of the reusable medical instrumentation. In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow. In parallel, the time variation of the inactivation efficiency quantified by the log reduction of the initial Escherichia coli (E. coli) population is correlated with morphologic changes observed on the bacteria by scanning electron microscopy (SEM) for increasing afterglow exposure times. The effect of the afterglow exposure is also studied on pure lipid A and on lipid A extracted from exposed E. coli bacteria. We report that more than 60% of lipid A (pure or bacteria-extracted) are lost with the used operating conditions (nitrogen flow QN2 = 1 standard liter per minute (slpm), pressure p = 5 Torr, microwave injected power PMW = 200 W, exposure time: 40 minutes). The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted) lipid A. Altogether these results point out the ability of reduced pressure nitrogen afterglows to neutralize the cytotoxic components in Gram-negative bacteria.

No MeSH data available.


Related in: MedlinePlus