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New insight into the residual inactivation of Microcystis aeruginosa by dielectric barrier discharge.

Li L, Zhang H, Huang Q - Sci Rep (2015)

Bottom Line: Our results showed that the numbers of both dead and apoptotic cells increased with DBD treatment delay time, and hydrogen peroxide produced by DBD was the main reason for the time-delayed inactivation effect.However, apart from the influence of hydrogen peroxide, the DBD-induced initial injures on the algal cells during the discharge period also played a considerable role in the inactivation of the DBD treated cells, as indicated by the measurement of intracellular reactive oxygen species (ROS) inside the algal cells.We therefore propose an effective approach to utilization of non-thermal plasma technique that makes good use of the residual inactivation effect to optimize the experimental conditions in terms of discharge time and delay time, so that more efficient treatment of cyanobacterial blooms can be achieved.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Ion Beam Bio-engineering, Institute of Biotechnology and Agriculture Engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, 230031.

ABSTRACT
We report the new insight into the dielectric barrier discharge (DBD) induced inactivation of Microcystis aeruginosa, the dominant algae which caused harmful cyanobacterial blooms in many developing countries. In contrast with the previous work, we employed flow cytometry to examine the algal cells, so that we could assess the dead and living cells with more accuracy, and distinguish an intermediate state of algal cells which were verified as apoptotic. Our results showed that the numbers of both dead and apoptotic cells increased with DBD treatment delay time, and hydrogen peroxide produced by DBD was the main reason for the time-delayed inactivation effect. However, apart from the influence of hydrogen peroxide, the DBD-induced initial injures on the algal cells during the discharge period also played a considerable role in the inactivation of the DBD treated cells, as indicated by the measurement of intracellular reactive oxygen species (ROS) inside the algal cells. We therefore propose an effective approach to utilization of non-thermal plasma technique that makes good use of the residual inactivation effect to optimize the experimental conditions in terms of discharge time and delay time, so that more efficient treatment of cyanobacterial blooms can be achieved.

No MeSH data available.


Detection of the apoptosis process after DBD plasma discharge.(a–c) TUNEL assay, (d–f) Flow cytometry assay for inactivation rate, (g–i) Caspase-3 activity assay. a,d,g: Untreated cells, b,e,h: DBD treated for 4 minutes, c,f,i: 5 hours after DBD treated for 4 minutes. The region which the red arrows point to shows the apoptotic cells.
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f3: Detection of the apoptosis process after DBD plasma discharge.(a–c) TUNEL assay, (d–f) Flow cytometry assay for inactivation rate, (g–i) Caspase-3 activity assay. a,d,g: Untreated cells, b,e,h: DBD treated for 4 minutes, c,f,i: 5 hours after DBD treated for 4 minutes. The region which the red arrows point to shows the apoptotic cells.

Mentions: We speculated that these cells were apoptotic cells or apoptotic-like cells30. To verify this, we then conducted the apoptosis assays, namely, terminal deoxynucleotidyl transferase labeling (TUNEL) assay and caspase-3 assay, and the results are illustrated in Fig. 3. The middle panel of Fig. 3 presents the result of flow cytometry, demonstrating three different states of the DBD treated cells. Correspondingly, the upper and lower panels of Fig. 3 are the fluorescent images of the algal cells: the red spots in the images are living and dead cells with auto-fluorescence, while the green spots are apoptotic cells labeled with the fluorescent dye by the apoptosis kits. It has been reported that sole H2O2 treatment can lead to apoptosis of algal cells, and indeed, this was also checked and verified by our own experiments (Supplementary Fig. S3 and Fig. S4). Therefore, compared with the cells without DBD treatment (Fig. 3a,d,g), both the TUNEL assay (Fig. 3a–c) and caspase-3 assay (Fig. 3g–i) confirm that DBD treatment can indeed lead to apoptosis of algae. In addition, we also examined the algal cells 5 hours later after the DBD treatment (Fig. 3c,f,i). Compared with the measurement from the DBD treated sample without delay (or the delay time is substantially short enough), the number of apoptotic cells is larger, indicating that elongation of both discharge time and delay time can make the remarkable contribution to apoptosis of algae.


New insight into the residual inactivation of Microcystis aeruginosa by dielectric barrier discharge.

Li L, Zhang H, Huang Q - Sci Rep (2015)

Detection of the apoptosis process after DBD plasma discharge.(a–c) TUNEL assay, (d–f) Flow cytometry assay for inactivation rate, (g–i) Caspase-3 activity assay. a,d,g: Untreated cells, b,e,h: DBD treated for 4 minutes, c,f,i: 5 hours after DBD treated for 4 minutes. The region which the red arrows point to shows the apoptotic cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561898&req=5

f3: Detection of the apoptosis process after DBD plasma discharge.(a–c) TUNEL assay, (d–f) Flow cytometry assay for inactivation rate, (g–i) Caspase-3 activity assay. a,d,g: Untreated cells, b,e,h: DBD treated for 4 minutes, c,f,i: 5 hours after DBD treated for 4 minutes. The region which the red arrows point to shows the apoptotic cells.
Mentions: We speculated that these cells were apoptotic cells or apoptotic-like cells30. To verify this, we then conducted the apoptosis assays, namely, terminal deoxynucleotidyl transferase labeling (TUNEL) assay and caspase-3 assay, and the results are illustrated in Fig. 3. The middle panel of Fig. 3 presents the result of flow cytometry, demonstrating three different states of the DBD treated cells. Correspondingly, the upper and lower panels of Fig. 3 are the fluorescent images of the algal cells: the red spots in the images are living and dead cells with auto-fluorescence, while the green spots are apoptotic cells labeled with the fluorescent dye by the apoptosis kits. It has been reported that sole H2O2 treatment can lead to apoptosis of algal cells, and indeed, this was also checked and verified by our own experiments (Supplementary Fig. S3 and Fig. S4). Therefore, compared with the cells without DBD treatment (Fig. 3a,d,g), both the TUNEL assay (Fig. 3a–c) and caspase-3 assay (Fig. 3g–i) confirm that DBD treatment can indeed lead to apoptosis of algae. In addition, we also examined the algal cells 5 hours later after the DBD treatment (Fig. 3c,f,i). Compared with the measurement from the DBD treated sample without delay (or the delay time is substantially short enough), the number of apoptotic cells is larger, indicating that elongation of both discharge time and delay time can make the remarkable contribution to apoptosis of algae.

Bottom Line: Our results showed that the numbers of both dead and apoptotic cells increased with DBD treatment delay time, and hydrogen peroxide produced by DBD was the main reason for the time-delayed inactivation effect.However, apart from the influence of hydrogen peroxide, the DBD-induced initial injures on the algal cells during the discharge period also played a considerable role in the inactivation of the DBD treated cells, as indicated by the measurement of intracellular reactive oxygen species (ROS) inside the algal cells.We therefore propose an effective approach to utilization of non-thermal plasma technique that makes good use of the residual inactivation effect to optimize the experimental conditions in terms of discharge time and delay time, so that more efficient treatment of cyanobacterial blooms can be achieved.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Ion Beam Bio-engineering, Institute of Biotechnology and Agriculture Engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, 230031.

ABSTRACT
We report the new insight into the dielectric barrier discharge (DBD) induced inactivation of Microcystis aeruginosa, the dominant algae which caused harmful cyanobacterial blooms in many developing countries. In contrast with the previous work, we employed flow cytometry to examine the algal cells, so that we could assess the dead and living cells with more accuracy, and distinguish an intermediate state of algal cells which were verified as apoptotic. Our results showed that the numbers of both dead and apoptotic cells increased with DBD treatment delay time, and hydrogen peroxide produced by DBD was the main reason for the time-delayed inactivation effect. However, apart from the influence of hydrogen peroxide, the DBD-induced initial injures on the algal cells during the discharge period also played a considerable role in the inactivation of the DBD treated cells, as indicated by the measurement of intracellular reactive oxygen species (ROS) inside the algal cells. We therefore propose an effective approach to utilization of non-thermal plasma technique that makes good use of the residual inactivation effect to optimize the experimental conditions in terms of discharge time and delay time, so that more efficient treatment of cyanobacterial blooms can be achieved.

No MeSH data available.