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Degradation and inactivation of Shiga toxins by nitrogen gas plasma

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ABSTRACT

Shiga toxin (Stx)-producing Escherichia coli (STEC) leads to food poisoning by causing hemorrhagic colitis and hemolytic uremic syndrome. Some STEC produce Shiga toxin 1 (Stx1) and/or Shiga toxin 2 (Stx2), a relatively stable protein toxin, necessitating the development of an efficient inactivation method. Here we applied a nitrogen gas plasma apparatus to the inactivation of Stx. Samples of Stx1 and Stx2 were treated with a nitrogen gas plasma generated by a plasma device using a short high-voltage pulse applied by a static induction thyristor power supply at 1.5 kpps (kilo pulse per second). The recovered Stx samples were then analyzed for immunological and biological activities. Immunochromatography demonstrated that Stx1 and Stx2 were degraded by the gas plasma. Quantification by enzyme-linked immunosorbent assay (ELISA) showed that both toxins were efficiently degraded to less than 1/10th of their original concentration within 5 min of treatment. Western blotting further showed the gas plasma treatment degraded the A subunit, which mediates the toxicity of Stx. Moreover, an assay using HEp-2 cells as an index of cytotoxicity showed that gas plasma treatment reduced the toxic activity of Stx. Therefore, nitrogen gas plasma might be an efficient method for the inactivation of Stx.

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Immunochromatography of Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2) after nitrogen gas plasma treatment. A coverslip containing dried spots from 20 μl aliquots of a 1 μg/ml solution of Shiga toxins (Stx) including Stx1 (a) and Stx2 (b) was treated with nitrogen gas plasma using a bi-polar and low-pressure plasma-triple effects sterilization (BLP-TES) device (1.5 kpps) for 0, 5, 15, or 30 min. The recovered Stx1 and Stx2 samples were analyzed by immunochromatography using an NH immunochromato VT1/2 kit (NH Foods Ltd., Osaka, Japan). Test lines for Stx1 and Stx2, and reference lines for the internal control are indicated by arrows
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Fig1: Immunochromatography of Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2) after nitrogen gas plasma treatment. A coverslip containing dried spots from 20 μl aliquots of a 1 μg/ml solution of Shiga toxins (Stx) including Stx1 (a) and Stx2 (b) was treated with nitrogen gas plasma using a bi-polar and low-pressure plasma-triple effects sterilization (BLP-TES) device (1.5 kpps) for 0, 5, 15, or 30 min. The recovered Stx1 and Stx2 samples were analyzed by immunochromatography using an NH immunochromato VT1/2 kit (NH Foods Ltd., Osaka, Japan). Test lines for Stx1 and Stx2, and reference lines for the internal control are indicated by arrows

Mentions: First, the treated Stx1 and Stx2 were subjected to immunochromatography (Fig. 1). The results showed that the test lines of Stx1 were diminished by gas plasma treatment for 5, 15 and 30 min, as compared with the untreated sample (0 min) (Fig. 1a). In the case of Stx2, test lines were detected in the untreated sample (0 min) and the sample treated for 5 min, but were diminished in samples treated for 15 and 30 min (Fig. 1b).Fig. 1


Degradation and inactivation of Shiga toxins by nitrogen gas plasma
Immunochromatography of Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2) after nitrogen gas plasma treatment. A coverslip containing dried spots from 20 μl aliquots of a 1 μg/ml solution of Shiga toxins (Stx) including Stx1 (a) and Stx2 (b) was treated with nitrogen gas plasma using a bi-polar and low-pressure plasma-triple effects sterilization (BLP-TES) device (1.5 kpps) for 0, 5, 15, or 30 min. The recovered Stx1 and Stx2 samples were analyzed by immunochromatography using an NH immunochromato VT1/2 kit (NH Foods Ltd., Osaka, Japan). Test lines for Stx1 and Stx2, and reference lines for the internal control are indicated by arrows
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383910&req=5

Fig1: Immunochromatography of Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2) after nitrogen gas plasma treatment. A coverslip containing dried spots from 20 μl aliquots of a 1 μg/ml solution of Shiga toxins (Stx) including Stx1 (a) and Stx2 (b) was treated with nitrogen gas plasma using a bi-polar and low-pressure plasma-triple effects sterilization (BLP-TES) device (1.5 kpps) for 0, 5, 15, or 30 min. The recovered Stx1 and Stx2 samples were analyzed by immunochromatography using an NH immunochromato VT1/2 kit (NH Foods Ltd., Osaka, Japan). Test lines for Stx1 and Stx2, and reference lines for the internal control are indicated by arrows
Mentions: First, the treated Stx1 and Stx2 were subjected to immunochromatography (Fig. 1). The results showed that the test lines of Stx1 were diminished by gas plasma treatment for 5, 15 and 30 min, as compared with the untreated sample (0 min) (Fig. 1a). In the case of Stx2, test lines were detected in the untreated sample (0 min) and the sample treated for 5 min, but were diminished in samples treated for 15 and 30 min (Fig. 1b).Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

Shiga toxin (Stx)-producing Escherichia coli (STEC) leads to food poisoning by causing hemorrhagic colitis and hemolytic uremic syndrome. Some STEC produce Shiga toxin 1 (Stx1) and/or Shiga toxin 2 (Stx2), a relatively stable protein toxin, necessitating the development of an efficient inactivation method. Here we applied a nitrogen gas plasma apparatus to the inactivation of Stx. Samples of Stx1 and Stx2 were treated with a nitrogen gas plasma generated by a plasma device using a short high-voltage pulse applied by a static induction thyristor power supply at 1.5 kpps (kilo pulse per second). The recovered Stx samples were then analyzed for immunological and biological activities. Immunochromatography demonstrated that Stx1 and Stx2 were degraded by the gas plasma. Quantification by enzyme-linked immunosorbent assay (ELISA) showed that both toxins were efficiently degraded to less than 1/10th of their original concentration within 5 min of treatment. Western blotting further showed the gas plasma treatment degraded the A subunit, which mediates the toxicity of Stx. Moreover, an assay using HEp-2 cells as an index of cytotoxicity showed that gas plasma treatment reduced the toxic activity of Stx. Therefore, nitrogen gas plasma might be an efficient method for the inactivation of Stx.

No MeSH data available.


Related in: MedlinePlus