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Effects of Carbon Dioxide Aerosols on the Viability of Escherichia coli during Biofilm Dispersal.

Singh R, Monnappa AK, Hong S, Mitchell RJ, Jang J - Sci Rep (2015)

Bottom Line: A periodic jet of carbon dioxide (CO2) aerosols is a very quick and effective mechanical technique to remove biofilms from various substrate surfaces.Indirect proof that the aerosols are damaging the bacteria was found using a recombinant E. coli expressing the cyan fluorescent protein, as nearly half of the fluorescence was found in the supernatant after CO2 aerosol treatment, while the rest was associated with the bacterial pellet.In comparison, the supernatant fluorescence was only 9% when the enzymes were used to disperse the biofilm.

View Article: PubMed Central - PubMed

Affiliation: School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, S. Korea.

ABSTRACT
A periodic jet of carbon dioxide (CO2) aerosols is a very quick and effective mechanical technique to remove biofilms from various substrate surfaces. However, the impact of the aerosols on the viability of bacteria during treatment has never been evaluated. In this study, the effects of high-speed CO2 aerosols, a mixture of solid and gaseous CO2, on bacteria viability was studied. It was found that when CO2 aerosols were used to disperse biofilms of Escherichia coli, they led to a significant loss of viability, with approximately 50% of the dispersed bacteria killed in the process. By comparison, 75.6% of the biofilm-associated bacteria were viable when gently dispersed using Proteinase K and DNase I. Indirect proof that the aerosols are damaging the bacteria was found using a recombinant E. coli expressing the cyan fluorescent protein, as nearly half of the fluorescence was found in the supernatant after CO2 aerosol treatment, while the rest was associated with the bacterial pellet. In comparison, the supernatant fluorescence was only 9% when the enzymes were used to disperse the biofilm. As such, these CO2 aerosols not only remove biofilm-associated bacteria effectively but also significantly impact their viability by disrupting membrane integrity.

No MeSH data available.


Related in: MedlinePlus

Viable number of E. coli present within the CO2 aerosol treated samples.(a) Colony forming units determined by plating out on agar plates. The samples are the Control, which was gently dispersed using a Proteinase K and DNase I treatment, the Aerosol sample, i.e. the bacteria dispersed by CO2 aerosols and captured within the flask, and the Aero + Chip sample, which includes both the flask captured bacteria and the dispersal of any remaining bacteria present on the chip using Proteinase K and DNase I. (b) The relative fluorescence seen in the whole sample or the constituent parts (i.e., cell pellet or supernatant). The presence of nearly half of the fluorescence in the supernatant after CO2 aerosol treatment implies that a significant number of E. coli are being ruptured by this treatment. Statistical analysis was performed using one-way ANOVA followed by the Tukey post hoc test. Statistically significant results are identified with asterisks (*,** =P values < 0.05 or 0.01, respectively; ns – not significant).
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f3: Viable number of E. coli present within the CO2 aerosol treated samples.(a) Colony forming units determined by plating out on agar plates. The samples are the Control, which was gently dispersed using a Proteinase K and DNase I treatment, the Aerosol sample, i.e. the bacteria dispersed by CO2 aerosols and captured within the flask, and the Aero + Chip sample, which includes both the flask captured bacteria and the dispersal of any remaining bacteria present on the chip using Proteinase K and DNase I. (b) The relative fluorescence seen in the whole sample or the constituent parts (i.e., cell pellet or supernatant). The presence of nearly half of the fluorescence in the supernatant after CO2 aerosol treatment implies that a significant number of E. coli are being ruptured by this treatment. Statistical analysis was performed using one-way ANOVA followed by the Tukey post hoc test. Statistically significant results are identified with asterisks (*,** =P values < 0.05 or 0.01, respectively; ns – not significant).

Mentions: Removal of biofilms with CO2 aerosols was previously demonstrated by our group1920. Based upon the above images and a previous report4, it is clear that biofilms harbor a significant number of viable bacteria. However, the effects of CO2 aerosols on the viability of the dispersed bacteria have not been studied to date. To evaluate this, therefore, we collected three groups of samples: enzymatically dispersed bacteria from a biofilm using Proteinase K and DNase I (Control), the bacteria dispersed from the biofilm by CO2 aerosols (Aerosol) and those obtained after treatment of the biofilm first by CO2 aerosols followed by an enzymatic treatment of the biofilm still attached to the silicon chip (Aero + Chip). It should be noted that all the samples collected were treated subsequently with Proteinase K and DNase I to dissociate any bacterial aggregates that were present to ensure that the viable counts in Fig. 3a were correct.


Effects of Carbon Dioxide Aerosols on the Viability of Escherichia coli during Biofilm Dispersal.

Singh R, Monnappa AK, Hong S, Mitchell RJ, Jang J - Sci Rep (2015)

Viable number of E. coli present within the CO2 aerosol treated samples.(a) Colony forming units determined by plating out on agar plates. The samples are the Control, which was gently dispersed using a Proteinase K and DNase I treatment, the Aerosol sample, i.e. the bacteria dispersed by CO2 aerosols and captured within the flask, and the Aero + Chip sample, which includes both the flask captured bacteria and the dispersal of any remaining bacteria present on the chip using Proteinase K and DNase I. (b) The relative fluorescence seen in the whole sample or the constituent parts (i.e., cell pellet or supernatant). The presence of nearly half of the fluorescence in the supernatant after CO2 aerosol treatment implies that a significant number of E. coli are being ruptured by this treatment. Statistical analysis was performed using one-way ANOVA followed by the Tukey post hoc test. Statistically significant results are identified with asterisks (*,** =P values < 0.05 or 0.01, respectively; ns – not significant).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4561891&req=5

f3: Viable number of E. coli present within the CO2 aerosol treated samples.(a) Colony forming units determined by plating out on agar plates. The samples are the Control, which was gently dispersed using a Proteinase K and DNase I treatment, the Aerosol sample, i.e. the bacteria dispersed by CO2 aerosols and captured within the flask, and the Aero + Chip sample, which includes both the flask captured bacteria and the dispersal of any remaining bacteria present on the chip using Proteinase K and DNase I. (b) The relative fluorescence seen in the whole sample or the constituent parts (i.e., cell pellet or supernatant). The presence of nearly half of the fluorescence in the supernatant after CO2 aerosol treatment implies that a significant number of E. coli are being ruptured by this treatment. Statistical analysis was performed using one-way ANOVA followed by the Tukey post hoc test. Statistically significant results are identified with asterisks (*,** =P values < 0.05 or 0.01, respectively; ns – not significant).
Mentions: Removal of biofilms with CO2 aerosols was previously demonstrated by our group1920. Based upon the above images and a previous report4, it is clear that biofilms harbor a significant number of viable bacteria. However, the effects of CO2 aerosols on the viability of the dispersed bacteria have not been studied to date. To evaluate this, therefore, we collected three groups of samples: enzymatically dispersed bacteria from a biofilm using Proteinase K and DNase I (Control), the bacteria dispersed from the biofilm by CO2 aerosols (Aerosol) and those obtained after treatment of the biofilm first by CO2 aerosols followed by an enzymatic treatment of the biofilm still attached to the silicon chip (Aero + Chip). It should be noted that all the samples collected were treated subsequently with Proteinase K and DNase I to dissociate any bacterial aggregates that were present to ensure that the viable counts in Fig. 3a were correct.

Bottom Line: A periodic jet of carbon dioxide (CO2) aerosols is a very quick and effective mechanical technique to remove biofilms from various substrate surfaces.Indirect proof that the aerosols are damaging the bacteria was found using a recombinant E. coli expressing the cyan fluorescent protein, as nearly half of the fluorescence was found in the supernatant after CO2 aerosol treatment, while the rest was associated with the bacterial pellet.In comparison, the supernatant fluorescence was only 9% when the enzymes were used to disperse the biofilm.

View Article: PubMed Central - PubMed

Affiliation: School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, S. Korea.

ABSTRACT
A periodic jet of carbon dioxide (CO2) aerosols is a very quick and effective mechanical technique to remove biofilms from various substrate surfaces. However, the impact of the aerosols on the viability of bacteria during treatment has never been evaluated. In this study, the effects of high-speed CO2 aerosols, a mixture of solid and gaseous CO2, on bacteria viability was studied. It was found that when CO2 aerosols were used to disperse biofilms of Escherichia coli, they led to a significant loss of viability, with approximately 50% of the dispersed bacteria killed in the process. By comparison, 75.6% of the biofilm-associated bacteria were viable when gently dispersed using Proteinase K and DNase I. Indirect proof that the aerosols are damaging the bacteria was found using a recombinant E. coli expressing the cyan fluorescent protein, as nearly half of the fluorescence was found in the supernatant after CO2 aerosol treatment, while the rest was associated with the bacterial pellet. In comparison, the supernatant fluorescence was only 9% when the enzymes were used to disperse the biofilm. As such, these CO2 aerosols not only remove biofilm-associated bacteria effectively but also significantly impact their viability by disrupting membrane integrity.

No MeSH data available.


Related in: MedlinePlus