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Tamai S, Okuno M, Ogura Y, Suzuki Y. Genetic diversity of dissolved free extracellular DNA compared to intracellular DNA in wastewater treatment plants. THE SCIENCE OF THE TOTAL ENVIRONMENT 2025; 970:178989. [PMID: 40048953 DOI: 10.1016/j.scitotenv.2025.178989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2024] [Revised: 02/20/2025] [Accepted: 02/24/2025] [Indexed: 03/17/2025]
Abstract
Dissolved free extracellular DNA (free-exDNA) coexists with intracellular DNA (inDNA) in aquatic environments. Free-exDNA can be taken up by bacteria through transformation, and wastewater treatment plants (WWTPs) are positioned as potential hot spots for genetic contamination. However, studies comparing the composition of free-exDNA and inDNA is limited. This study employed colloidal adsorption and foam concentration method to recover free-exDNA from different WWTP stages and compared its diversity with inDNA via metagenomic analysis. Free-exDNA concentrations were observed to increase after chlorination. Genetic analysis revealed a higher abundance of specific genes following chlorination, suggesting that free-exDNA in effluent originated from bacterial death in secondary treated water. This result indicates that free-exDNA, which increases due to chlorination, is subsequently released into the catchment. Additionally, several high-risk antibiotic-resistance genes (ARGs) were detected that colocalized with mobile genetic elements. These ARGs were expected to have a high potential for gene transfer via transformation, and the risk was highlighted. Overall, these findings deepen our understanding of horizontal gene transfer risks in WWTPs.
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Affiliation(s)
- Soichiro Tamai
- Department of Environment and Resource Sciences, Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki, Gakuen Kibanadai-Nishi 1-1, Miyazaki 889-2192, Japan.
| | - Miki Okuno
- Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan.
| | - Yoshitoshi Ogura
- Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan.
| | - Yoshihiro Suzuki
- Department of Civil and Environmental Engineering, Faculty of Engineering, University of Miyazaki, Gakuen Kibanadai-Nishi 1-1, Miyazaki 889-2192, Japan.
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Zheng F, Zhu X, Liu Y, Yu X, Wang L. Integrated inactivation of Microcystis aeruginosa and degradation of microcystin-LR by direct current glow discharge plasma in liquid-phase: Mechanisms and cell deactivation process. JOURNAL OF HAZARDOUS MATERIALS 2025; 484:136738. [PMID: 39637788 DOI: 10.1016/j.jhazmat.2024.136738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2024] [Revised: 11/21/2024] [Accepted: 11/30/2024] [Indexed: 12/07/2024]
Abstract
The frequent occurrence of blooms of Microcystis aeruginosa (M. aeruginosa) and the subsequent release of microcystin-LR (MC-LR) in eutrophic waters pose a serious threat to aquatic ecosystems. This study investigated the optimal conditions for inactivating M. aeruginosa and the degrading MC-LR using direct current glow discharge plasma in liquid phase (DC-LGDP), analyzed the potential inactivation mechanisms and the cell deactivation process of M. aeruginosa. The results showed that DC-LGDP generated reactive species (i.e., •OH, 1O2, and H2O2), active Cl and electroporation effect collectively contributed to inactivation of M. aeruginosa and degradation of MC-LR. The 97.07 % inactivation efficiency of M. aeruginosa and 94.98 % degradation rate of MC-LR were achieved with higher energy yield and without generating nitrogen oxides. Meanwhile, DC-LGDP destroyed the cell integrity, eliminated their antioxidant capacity and reduced the content of photosynthetic pigments. The transcriptome analysis indicated that the transcripts of genes related to photosynthesis, ribosome biosynthesis, ABC transporters, and nitrogen metabolism pathway in M. aeruginosa were altered by DC-LGDP. This study provides insights into the inactivation of M. aeruginosa by DC-LGDP, while elucidating the potential inactivation mechanisms and the cell deactivation process involved. It may be important for the eco-friendly inactivation of M. aeruginosa blooms in natural water bodies.
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Affiliation(s)
- Feng Zheng
- School of Environmental Science & Engineering, Xiamen University of Technology, Xiamen 361024, China
| | - Xinhong Zhu
- School of Environmental Science & Engineering, Xiamen University of Technology, Xiamen 361024, China
| | - Yanyan Liu
- School of Environmental Science & Engineering, Xiamen University of Technology, Xiamen 361024, China
| | - Xin Yu
- Fujian Key Laboratory of Coastal Pollution Prevention and Control, College of the Environment & Ecology, Xiamen University, Xiamen 361102, China
| | - Lei Wang
- School of Environmental Science & Engineering, Xiamen University of Technology, Xiamen 361024, China.
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Zhao Q, Xu Z, Liu X, Zhu H, Li Z, Liu Y, Yang J, Dong Q. Formation and recovery of Listeria monocytogenes in viable but nonculturable state under different temperatures combined with low nutrition and high NaCl concentration. Food Res Int 2024; 192:114774. [PMID: 39147498 DOI: 10.1016/j.foodres.2024.114774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Revised: 06/21/2024] [Accepted: 07/14/2024] [Indexed: 08/17/2024]
Abstract
The viable but nonculturable (VBNC) state occurs when bacteria lose their ability to grow and multiply on conventional media when stressed by adverse environmental factors, but they remain active and can revive under certain conditions, posing a food safety risk. In this study, the VBNC state of Listeria monocytogenes was induced with different temperatures combined with low nutrient conditions; the VBNC state of L. monocytogenes was confirmed in conjunction with the housekeeping gene abcZ using a molecular biology assay (PMA-qPCR) to calculate the viable bacterial count; The resuscitation conditions for the VBNC state of L. monocytogenes were investigated utilizing various nutrients in the culture medium and pasteurized milk. Four strains of L. monocytogenes reached the VBNC stage after 14, 21, 21, and 35 days at 20°C with 20% (or 30%) NaCl. Resuscitation studies indicate that Trypticase Soy Broth (TSB) combined with Tween 80 and sodium pyruvate is more effective for resuscitation. The Chinese national standard technology GB 4789.30-2016 was used to inoculate lettuce, chicken, and pasteurized milk with L. monocytogenes ATCC 19115 VBNC state. This research has significant implications for commercial food processing, long-term storage, disinfection, disease prevention, and control.
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Affiliation(s)
- Qing Zhao
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Zhiwen Xu
- Technical Center for Animal, Plant and Food Inspection and Quarantine of Shanghai Customs, 299 Mian Bei Rd., Shanghai 201210, China.
| | - Xin Liu
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Huajian Zhu
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Zhuosi Li
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Yangtai Liu
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Jielin Yang
- Technical Center for Animal, Plant and Food Inspection and Quarantine of Shanghai Customs, 299 Mian Bei Rd., Shanghai 201210, China.
| | - Qingli Dong
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
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4
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Li Y, Wei L, Lin J, Xie Z, Lu L, Pan X, Xu J, Cai R. Nonthermal plasma air disinfection for the inactivation of airborne microorganisms in an experimental chamber and indoor air. J Appl Microbiol 2024; 135:lxae078. [PMID: 38520159 DOI: 10.1093/jambio/lxae078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 02/28/2024] [Accepted: 03/21/2024] [Indexed: 03/25/2024]
Abstract
AIMS Airborne transmission of diseases presents a serious threat to human health, so effective air disinfection technology to eliminate microorganisms in indoor air is very important. This study evaluated the effectiveness of a non-thermal plasma (NTP) air disinfector in both laboratory experiments and real environments. METHODS AND RESULTS An experimental chamber was artificially polluted with a bioaerosol containing bacteria or viruses. Additionally, classroom environments with and without people present were used in field tests. Airborne microbial and particle concentrations were quantified. A 3.0 log10 reduction in the initial load was achieved when a virus-containing aerosol was disinfected for 60 min and a bacteria-containing aerosol was disinfected for 90 min. In the field test, when no people were present in the room, NTP disinfection decreased the airborne microbial and particle concentrations (P < 0.05). When people were present in the room, their constant activity continuously contaminated the indoor air, but all airborne indicators decreased (P < 0.05) except for planktonic bacteria (P = 0.094). CONCLUSIONS NTP effectively inactivated microorganisms and particles in indoor air.
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Affiliation(s)
- Ye Li
- Department of Environmental Health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
| | - Lanfen Wei
- Department of Environmental Health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
| | - Junming Lin
- Department of Environmental Health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
| | - Zhongyi Xie
- Department of Environmental Health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
| | - Longxi Lu
- Department of Environmental Health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
| | - Xieshang Pan
- Department of Environmental Health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
| | - Ji Xu
- Department of Environmental Health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
| | - Ran Cai
- Department of Environmental Health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China
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Mamba PP, Msagati TAM, Mamba BB, Motsa MM, Nkambule TTI. The removal of pathogenic bacteria and dissolved organic matter from freshwater using microporous membranes: insights into biofilm formation and fouling reversibility. BIOFOULING 2024; 40:245-261. [PMID: 38639133 DOI: 10.1080/08927014.2024.2339438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 04/01/2024] [Indexed: 04/20/2024]
Abstract
Pathogenic bacteria in drinking-water pose a health risk to consumers, as they compromise the quality of portable water. Chemical disinfection of water containing dissolved organic matter (DOM) causes harmful disinfection by-products. In this work, 4-hydroxybenzoic acid (4-HBA) blended polyethersulfone membranes were fabricated and characterised using microscopic and spectroscopic techniques. The membranes were evaluated for the removal of bacteria and DOM from synthetic and environmental water. Permeate flux increased from 287.30 to 374.60 l m-2 h-1 at 3 bars when 4-HBA increased from 0 to 1.5 wt.%, suggesting that 4-HBA influenced the membrane's affinity for water. Furthermore, 4-HBA demonstrated antimicrobial properties by inhibiting bacterial growth. The membrane with 1 wt.% 4-HBA recorded 99.4 and 100% bacteria removal in synthetic and environmental water, respectively. Additionally, DOM removal of 55-73% was achieved. A flux recovery ratio (FRR) of 94.6% was obtained when a mixture of bacteria and humic acid was filtered, implying better fouling layer reversibility during cleaning. Furthermore, 100% FRR was achieved when a multimedia granular filtration step was installed prior to membrane filtration. The results illustrated that the membranes had a high permeate flux with low irreversible fouling. This indicated the potential of the membranes in treating complex feed streams using simple cleaning protocols.
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Affiliation(s)
- Phumlile P Mamba
- Institute for Nanotechnology and Water Sustainability (iNanoWS), College of Science, Engineering and Technology, University of South Africa, Science Campus, Florida, Johannesburg, South Africa
| | - Titus A M Msagati
- Institute for Nanotechnology and Water Sustainability (iNanoWS), College of Science, Engineering and Technology, University of South Africa, Science Campus, Florida, Johannesburg, South Africa
| | - Bhekie B Mamba
- Institute for Nanotechnology and Water Sustainability (iNanoWS), College of Science, Engineering and Technology, University of South Africa, Science Campus, Florida, Johannesburg, South Africa
| | - Machawe M Motsa
- Institute for Nanotechnology and Water Sustainability (iNanoWS), College of Science, Engineering and Technology, University of South Africa, Science Campus, Florida, Johannesburg, South Africa
| | - Thabo T I Nkambule
- Institute for Nanotechnology and Water Sustainability (iNanoWS), College of Science, Engineering and Technology, University of South Africa, Science Campus, Florida, Johannesburg, South Africa
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Hu D, Li X, Zeng J, Xiao X, Zhao W, Zhang J, Yu X. Hidden risks: Simulated leakage of domestic sewage to secondary water supply systems poses serious microbiological risks. WATER RESEARCH 2023; 244:120529. [PMID: 37666151 DOI: 10.1016/j.watres.2023.120529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 08/22/2023] [Accepted: 08/25/2023] [Indexed: 09/06/2023]
Abstract
There are continuous reports about the pollution of the secondary water supply systems (SWSSs), among which domestic sewage leakage is the most serious. In this study, a pilot experiment lasting 70 days was conducted to explore the changes in physicochemical water quality and the microbial profiles in SWSSs polluted by different doses of domestic sewage through qPCR and high-throughput sequencing methods. The results showed that when domestic sewage entered the simulated water storage tank, a large amount of organic matter brought by domestic sewage quickly consumed chlorine disinfectants. High pollution levels (pollution index ≥ 1/1000) were accompanied by significant increases in turbidity and ammonia nitrogen concentration (p < 0.05) and by abnormal changes in sensory properties. Although different microbial community structures were found only at high pollution levels, qPCR results showed that the abundance of the bacterial 16S rRNA gene and some pathogenic gene markers in the polluted tank increased with the pollution level, and the specific gene marker of pathogens could be detected even at imperceptible pollution levels. In particular, the high detection frequency and abundance of Escherichia coli and Enterococcus faecails in polluted tank water samples demonstrated that they can be used for early warning. Moreover, it seems that the microorganisms that came with the domestic sewage lost their cultivability soon after entering SWSSs but could recover their activities during stagnation. In addition, the biofilm biomass in the polluted tank with high pollution levels increased faster at the initial stage, while after a longer contact time, it tended to remain at the same level as the control tank. This study emphasized the high microbial risk introduced by sewage water leakage even at imperceptible levels and could provide scientific suggestions for early warning and prevention of pollution to SWSSs.
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Affiliation(s)
- Dong Hu
- School of Public Health, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan 250117, China
| | - Xiang Li
- School of Public Health, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan 250117, China
| | - Jie Zeng
- Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Kyoto University Katsura, Nishikyo, Kyoto 615-8540, Japan
| | - Xinyan Xiao
- College of the Environment & Ecology, Xiamen University, Xiamen 361102, China
| | - Wenya Zhao
- College of the Environment & Ecology, Xiamen University, Xiamen 361102, China
| | - Jiakang Zhang
- College of the Environment & Ecology, Xiamen University, Xiamen 361102, China
| | - Xin Yu
- College of the Environment & Ecology, Xiamen University, Xiamen 361102, China.
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