Effects of pH and ultrasonication for decomposition of Microcystis formed colony in a bloom sample from a reservoir
In this study, we investigated the effects of pH and ultrasonication on Microcystis degradation in bloom samples consisting predominantly of colonial Microcystis. The biofilm-spiked bloom samples were incubated for 7 days with shaking at low pH (7−8) and high pH (9−10) conditions in the dark. This r...
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Elsevier
2025-04-01
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| Series: | Desalination and Water Treatment |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S194439862500219X |
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| author | Somsri Saenchan Kazuya Shimizu Norio Iwami Misigo W.S. Angalika Hideaki Maseda Nguyen Binh Minh Huynh V. Vu Le-Huynh Truc-Ly Tomoaki Itayam |
| author_facet | Somsri Saenchan Kazuya Shimizu Norio Iwami Misigo W.S. Angalika Hideaki Maseda Nguyen Binh Minh Huynh V. Vu Le-Huynh Truc-Ly Tomoaki Itayam |
| author_sort | Somsri Saenchan |
| collection | DOAJ |
| description | In this study, we investigated the effects of pH and ultrasonication on Microcystis degradation in bloom samples consisting predominantly of colonial Microcystis. The biofilm-spiked bloom samples were incubated for 7 days with shaking at low pH (7−8) and high pH (9−10) conditions in the dark. This resulted in a significant decrease in chlorophyll-a at the low pH condition compared to the high pH condition. Conversely, Bayesian regression analysis indicated that the difference in the degradation rate of Chl-a with and without ultrasonication treatment was not statistically significant. It was hypothesized that the dispersed cells rapidly reaggregated, which inhibited the degradation of Microcystis cells. The degradation rate of the IPC gene (intergenic spacer region within the phycocyanin operon) and the mcyB gene (microcystin synthesis gene) demonstrated enhanced degradation rates at low pH conditions relative to high pH conditions, as well as Chl-a. The proliferation of microfauna, including rotifers and protozoa, and the active predation of Microcystis cells were confirmed through microscopic observation under low pH conditions. Notwithstanding the high pH condition, some protozoan species were observed. However, many Microcystis cells and colonies remained. The comparison of the decomposition rates of the IPC gene and the mcyB gene using Bayesian analysis revealed that non-toxic were slightly more preferred than toxic Microcystis cells in the predation process. The estimated cost for adjusting the pH of a small eutrophicated reservoir to pH 7 using industrial sulfuric acid to enhance predation falls within the range of costs that could be considered for practical implementation. |
| format | Article |
| id | doaj-art-19042d84c4e443a5ab08da5e7a041e0c |
| institution | OA Journals |
| issn | 1944-3986 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Desalination and Water Treatment |
| spelling | doaj-art-19042d84c4e443a5ab08da5e7a041e0c2025-08-20T02:02:51ZengElsevierDesalination and Water Treatment1944-39862025-04-0132210120310.1016/j.dwt.2025.101203Effects of pH and ultrasonication for decomposition of Microcystis formed colony in a bloom sample from a reservoirSomsri Saenchan0Kazuya Shimizu1Norio Iwami2Misigo W.S. Angalika3Hideaki Maseda4Nguyen Binh Minh5Huynh V. Vu6Le-Huynh Truc-Ly7Tomoaki Itayam8Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanGraduate School of Life Sciences, Toyo University, 48-1 Ichioka, Asaka, Saitama 351-8510, JapanGraduate School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191- 8506, JapanGraduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanBiomedical Research Institute, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Osaka 563-8577, JapanGraduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanGraduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanGraduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan; UVA Environmental Institute, University of Virginia, 22902, Charlottesville, VA, 800318, USAGraduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan; Corresponding author.In this study, we investigated the effects of pH and ultrasonication on Microcystis degradation in bloom samples consisting predominantly of colonial Microcystis. The biofilm-spiked bloom samples were incubated for 7 days with shaking at low pH (7−8) and high pH (9−10) conditions in the dark. This resulted in a significant decrease in chlorophyll-a at the low pH condition compared to the high pH condition. Conversely, Bayesian regression analysis indicated that the difference in the degradation rate of Chl-a with and without ultrasonication treatment was not statistically significant. It was hypothesized that the dispersed cells rapidly reaggregated, which inhibited the degradation of Microcystis cells. The degradation rate of the IPC gene (intergenic spacer region within the phycocyanin operon) and the mcyB gene (microcystin synthesis gene) demonstrated enhanced degradation rates at low pH conditions relative to high pH conditions, as well as Chl-a. The proliferation of microfauna, including rotifers and protozoa, and the active predation of Microcystis cells were confirmed through microscopic observation under low pH conditions. Notwithstanding the high pH condition, some protozoan species were observed. However, many Microcystis cells and colonies remained. The comparison of the decomposition rates of the IPC gene and the mcyB gene using Bayesian analysis revealed that non-toxic were slightly more preferred than toxic Microcystis cells in the predation process. The estimated cost for adjusting the pH of a small eutrophicated reservoir to pH 7 using industrial sulfuric acid to enhance predation falls within the range of costs that could be considered for practical implementation.http://www.sciencedirect.com/science/article/pii/S194439862500219XPHUltrasonicationToxic MicrocystisNon-toxic MicrocystisMicrofaunaPredation |
| spellingShingle | Somsri Saenchan Kazuya Shimizu Norio Iwami Misigo W.S. Angalika Hideaki Maseda Nguyen Binh Minh Huynh V. Vu Le-Huynh Truc-Ly Tomoaki Itayam Effects of pH and ultrasonication for decomposition of Microcystis formed colony in a bloom sample from a reservoir Desalination and Water Treatment PH Ultrasonication Toxic Microcystis Non-toxic Microcystis Microfauna Predation |
| title | Effects of pH and ultrasonication for decomposition of Microcystis formed colony in a bloom sample from a reservoir |
| title_full | Effects of pH and ultrasonication for decomposition of Microcystis formed colony in a bloom sample from a reservoir |
| title_fullStr | Effects of pH and ultrasonication for decomposition of Microcystis formed colony in a bloom sample from a reservoir |
| title_full_unstemmed | Effects of pH and ultrasonication for decomposition of Microcystis formed colony in a bloom sample from a reservoir |
| title_short | Effects of pH and ultrasonication for decomposition of Microcystis formed colony in a bloom sample from a reservoir |
| title_sort | effects of ph and ultrasonication for decomposition of microcystis formed colony in a bloom sample from a reservoir |
| topic | PH Ultrasonication Toxic Microcystis Non-toxic Microcystis Microfauna Predation |
| url | http://www.sciencedirect.com/science/article/pii/S194439862500219X |
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