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Enhanced detection sensitivity of Escherichia coli O157:H7 using surface-modified gold nanorods.

Ramasamy M, Yi DK, An SS - Int J Nanomedicine (2015)

Bottom Line: Endogenous membrane peroxidase, an enzyme present on the surface of O157, was used for the colorimetric detection of bacteria by catalytic oxidation of the peroxidase substrate.In this study, we have analyzed the impact of the synthesized bare gold nanorods (AuNRs) and silica-coated AuNRs on the growth of E. coli O157.This result can be particularly important for the enzymatic analysis of surface treated AuNRs in various microbiological applicants.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical Engineering, Yeungnam University, Gyeongsan, Republic of Korea.

ABSTRACT
Escherichia coli O157:H7 (O157) is a Gram negative and highly virulent bacteria found in food and water sources, and is a leading cause of chronic diseases worldwide. Diagnosis and prevention from the infection require simple and rapid analysis methods for the detection of pathogens, including O157. Endogenous membrane peroxidase, an enzyme present on the surface of O157, was used for the colorimetric detection of bacteria by catalytic oxidation of the peroxidase substrate. In this study, we have analyzed the impact of the synthesized bare gold nanorods (AuNRs) and silica-coated AuNRs on the growth of E. coli O157. Along with the membrane peroxidase activity of O157, other bacteria strains were analyzed. Different concentrations of nanorods were used to analyze the growth responses, enzymatic changes, and morphological alterations of bacteria by measuring optical density, 3,3',5,5'-tetramethylbenzidine assay, flow cytometry analysis, and microscopy studies. The results revealed that O157 showed higher and continuous membrane peroxidase activity than other bacteria. Furthermore, O157 treated with bare AuNRs showed a decreased growth rate in comparison with the bacteria with surface modified AuNRs. Interestingly, silica-coated AuNRs favored the growth of bacteria and also increased membrane peroxidase activity. This result can be particularly important for the enzymatic analysis of surface treated AuNRs in various microbiological applicants.

No MeSH data available.


Related in: MedlinePlus

Repeated membrane peroxidase analysis of bacteria samples.Notes: OD450 values of the bacteria samples after repeated washings without the addition of stop solution. Inset: Photographs of the corresponding bacterial suspensions (EC – E. coli O157, EF – E. faecalis, BS – B. subtilis, and ST – S. typhi, respectively).Abbreviations: OD, optical density; E. coli O157, Escherichia coli O157; E. faecalis, Enterococcus faecalis; B. subtilis, Bacillus subtilis; S. typhi, Salmonella typhimurium.
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f4-ijn-10-179: Repeated membrane peroxidase analysis of bacteria samples.Notes: OD450 values of the bacteria samples after repeated washings without the addition of stop solution. Inset: Photographs of the corresponding bacterial suspensions (EC – E. coli O157, EF – E. faecalis, BS – B. subtilis, and ST – S. typhi, respectively).Abbreviations: OD, optical density; E. coli O157, Escherichia coli O157; E. faecalis, Enterococcus faecalis; B. subtilis, Bacillus subtilis; S. typhi, Salmonella typhimurium.

Mentions: After TMB assay for the first instance, the same bacteria samples were washed with water to remove the traces of the stop solution, and they were then analyzed again for continuous membrane peroxidase activity. Interestingly, we found that only E. coli O157 showed continuous enzymatic activity even after being washed more than five times with water compared with other bacteria (Figure 4). The inset picture depicts the visible color changes of the continuous enzymatic activity, where E. coli O157 produced yellow color (before adding stop solution) after repeated washings compared with other bacterial pathogens, which were colorless after washings. The possible reason can be that, E. coli O157 could internalize the TMB substrate thus producing repeated color. But, the exact reason for these enzymatic activity differences in bacteria are yet to be identified.


Enhanced detection sensitivity of Escherichia coli O157:H7 using surface-modified gold nanorods.

Ramasamy M, Yi DK, An SS - Int J Nanomedicine (2015)

Repeated membrane peroxidase analysis of bacteria samples.Notes: OD450 values of the bacteria samples after repeated washings without the addition of stop solution. Inset: Photographs of the corresponding bacterial suspensions (EC – E. coli O157, EF – E. faecalis, BS – B. subtilis, and ST – S. typhi, respectively).Abbreviations: OD, optical density; E. coli O157, Escherichia coli O157; E. faecalis, Enterococcus faecalis; B. subtilis, Bacillus subtilis; S. typhi, Salmonella typhimurium.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556300&req=5

f4-ijn-10-179: Repeated membrane peroxidase analysis of bacteria samples.Notes: OD450 values of the bacteria samples after repeated washings without the addition of stop solution. Inset: Photographs of the corresponding bacterial suspensions (EC – E. coli O157, EF – E. faecalis, BS – B. subtilis, and ST – S. typhi, respectively).Abbreviations: OD, optical density; E. coli O157, Escherichia coli O157; E. faecalis, Enterococcus faecalis; B. subtilis, Bacillus subtilis; S. typhi, Salmonella typhimurium.
Mentions: After TMB assay for the first instance, the same bacteria samples were washed with water to remove the traces of the stop solution, and they were then analyzed again for continuous membrane peroxidase activity. Interestingly, we found that only E. coli O157 showed continuous enzymatic activity even after being washed more than five times with water compared with other bacteria (Figure 4). The inset picture depicts the visible color changes of the continuous enzymatic activity, where E. coli O157 produced yellow color (before adding stop solution) after repeated washings compared with other bacterial pathogens, which were colorless after washings. The possible reason can be that, E. coli O157 could internalize the TMB substrate thus producing repeated color. But, the exact reason for these enzymatic activity differences in bacteria are yet to be identified.

Bottom Line: Endogenous membrane peroxidase, an enzyme present on the surface of O157, was used for the colorimetric detection of bacteria by catalytic oxidation of the peroxidase substrate.In this study, we have analyzed the impact of the synthesized bare gold nanorods (AuNRs) and silica-coated AuNRs on the growth of E. coli O157.This result can be particularly important for the enzymatic analysis of surface treated AuNRs in various microbiological applicants.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical Engineering, Yeungnam University, Gyeongsan, Republic of Korea.

ABSTRACT
Escherichia coli O157:H7 (O157) is a Gram negative and highly virulent bacteria found in food and water sources, and is a leading cause of chronic diseases worldwide. Diagnosis and prevention from the infection require simple and rapid analysis methods for the detection of pathogens, including O157. Endogenous membrane peroxidase, an enzyme present on the surface of O157, was used for the colorimetric detection of bacteria by catalytic oxidation of the peroxidase substrate. In this study, we have analyzed the impact of the synthesized bare gold nanorods (AuNRs) and silica-coated AuNRs on the growth of E. coli O157. Along with the membrane peroxidase activity of O157, other bacteria strains were analyzed. Different concentrations of nanorods were used to analyze the growth responses, enzymatic changes, and morphological alterations of bacteria by measuring optical density, 3,3',5,5'-tetramethylbenzidine assay, flow cytometry analysis, and microscopy studies. The results revealed that O157 showed higher and continuous membrane peroxidase activity than other bacteria. Furthermore, O157 treated with bare AuNRs showed a decreased growth rate in comparison with the bacteria with surface modified AuNRs. Interestingly, silica-coated AuNRs favored the growth of bacteria and also increased membrane peroxidase activity. This result can be particularly important for the enzymatic analysis of surface treated AuNRs in various microbiological applicants.

No MeSH data available.


Related in: MedlinePlus