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Prof. Xin Yu
Department of Environmental and Ecological Engineering, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China

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0 Drinking Water
0 Water Treatment
0 Microbiological contamination
0 Water Quality Assessment
0 Urban water infrastructure

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Journal article
Published: 25 June 2021 in Journal of Hazardous Materials
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Occurrence of successive cyanobacterial blooms in source waters can continuously impair drinking water quality. Previous studies have separately investigated potassium permanganate (KMnO4) to treat high-viability cyanobacteria at just one stage of either development or maintenance. However, maintenance stage exhibited significantly higher cell-density and extracellular organic matters (EOMs) than development stage, which may result in a different KMnO4 oxidation pattern. In this study, kinetics of oxidant decay, membrane integrity loss, and toxin degradation of high-viability cyanobacteria at both stages were compared. Results showed that cyanobacteria at maintenance stage became more resistant to KMnO4 oxidation than that at development stage, since elevated cell-density and more proteins involved in EOMs resulted in lower oxidant exposure at this stage. Meanwhile, elevated cyanobacterial biomass became the main competitors to decrease toxin degradation efficiency at maintenance stage, leading to incapacity to degrade extracellular toxin to below safety guideline of 1 μg L−1. Consequently, comparing with the best strategy for development stage (6 mg min L−1, no membrane damage), a higher oxidant exposure (12 mg min L−1) was recommended to treat cyanobacteria at maintenance stage even with slight membrane damage (19%), since it degraded extracellular toxin to below safety guideline and achieved the highest removal ratio of EOMs. Overall, this study demonstrated that stage of cyanobacteria can strongly affect KMnO4 oxidation pattern, and it is necessary for water supplies to optimize KMnO4 treatments depending on bloom stage.

ACS Style

Xi Li; Jie Zeng; Xin Yu. Different response pattern of cyanobacteria at development and maintenance stage to potassium permanganate oxidation. Journal of Hazardous Materials 2021, 419, 126492 .

AMA Style

Xi Li, Jie Zeng, Xin Yu. Different response pattern of cyanobacteria at development and maintenance stage to potassium permanganate oxidation. Journal of Hazardous Materials. 2021; 419 ():126492.

Chicago/Turabian Style

Xi Li; Jie Zeng; Xin Yu. 2021. "Different response pattern of cyanobacteria at development and maintenance stage to potassium permanganate oxidation." Journal of Hazardous Materials 419, no. : 126492.

Journal article
Published: 10 June 2021 in Water Research
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Cell-viability of cyanobacteria declines from development to decay stage during a successive bloom. Potassium permanganate (KMnO4) has demonstrated to be a superior pre-oxidant to treat high-viability cyanobacteria compared to other common oxidants (e.g., chlorine), but whether it is feasible to treat low-viability cyanobacteria is unknown. Here, effects of KMnO4 on membrane integrity, cyanotoxin fate and extracellular organic matters (EOMs) removal of high- and low-viability cyanobacteria were compared. Results showed that cell-viability of cyanobacteria could affect oxidant decay (kdecay), membrane damage (kloss), and cyanotoxin release (ki) and degradation (ke) during KMnO4 oxidation, similar to chlorination. However, unlike chlorination, initial low dosages of KMnO4 (0.5 and 1 mg L−1) minimized membrane damage for low-viability cyanobacteria (< 27 %), and continuously decrease extracellular cyanotoxins, extracellular organic matters (EOMs), and aromatic compounds to some degrees (P 2 mg L−1) caused severe membrane destruction (> 89 %) for low-viability cyanobacteria, leading to a fast increase of extracellular cyanotoxins within 1 h. However, total/extracellular cyanotoxins was oxidized to below the safety guideline of 1 μg L−1 after being dosed with sufficient oxidant exposure. EOMs and aromatic compounds were also reduced by 5–18 % (P<0.05). Additionally, KMnO4-assisted coagulation significantly improved the removal of low-viability cyanobacteria (2–5 fold). Consequently, KMnO4 could be a promising pre-oxidant to treat low-viability cyanobacteria at decay stage of a successive bloom.

ACS Style

Xi Li; Jie Zeng; Xin Yu. Potassium permanganate as a promising pre-oxidant to treat low-viability cyanobacteria and associated removal of cyanotoxins and extracellular organic matters. Water Research 2021, 117353 .

AMA Style

Xi Li, Jie Zeng, Xin Yu. Potassium permanganate as a promising pre-oxidant to treat low-viability cyanobacteria and associated removal of cyanotoxins and extracellular organic matters. Water Research. 2021; ():117353.

Chicago/Turabian Style

Xi Li; Jie Zeng; Xin Yu. 2021. "Potassium permanganate as a promising pre-oxidant to treat low-viability cyanobacteria and associated removal of cyanotoxins and extracellular organic matters." Water Research , no. : 117353.

Journal article
Published: 03 May 2021 in Science of The Total Environment
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The emergence of antibiotics and their corresponding antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have posed great challenges to the public health. The paper demonstrates the removal of co-existing tetracycline (TC), its resistant Escherichia coli (E. coli), and ARGs (tetA and tetR) in a mixed system by applying ferrate(VI) (FeVIO42−, Fe(VI)) at pH 7.0. TC was efficiently degraded by Fe(VI), and the rapid inactivation of the resistant E. coli was found with the complete loss of culturability. The results of flow cytometry suggested that the damage of membrane integrity and respiratory activity were highly correlated with the Fe(VI) dosages. Moreover, high-dose Fe(VI) eliminates 6 log10 viable but non-culturable (VBNC) cells and even breaks the cells into fragments. ARGs in extracellular form (e-ARGs) exhibited a high sensitivity of 4.44 log10 removal to Fe(VI). Comparatively, no removal of intracellular ARGs (i-ARGs) was observed due to the multi-protection of cellular structure and rapid decay of Fe(VI). The oxidized products of TC were assessed to be less toxic than the parent compound. Overall, this study demonstrated the superior efficiency and great promise of Fe(VI) on simultaneous removal of antibiotics and their related ARB and ARGs in water.

ACS Style

Yiting Zhang; Menglu Zhang; Chengsong Ye; Mingbao Feng; Kun Wan; Wenfang Lin; Virender K. Sharma; Xin Yu. Mechanistic insight of simultaneous removal of tetracycline and its related antibiotic resistance bacteria and genes by ferrate(VI). Science of The Total Environment 2021, 786, 147492 .

AMA Style

Yiting Zhang, Menglu Zhang, Chengsong Ye, Mingbao Feng, Kun Wan, Wenfang Lin, Virender K. Sharma, Xin Yu. Mechanistic insight of simultaneous removal of tetracycline and its related antibiotic resistance bacteria and genes by ferrate(VI). Science of The Total Environment. 2021; 786 ():147492.

Chicago/Turabian Style

Yiting Zhang; Menglu Zhang; Chengsong Ye; Mingbao Feng; Kun Wan; Wenfang Lin; Virender K. Sharma; Xin Yu. 2021. "Mechanistic insight of simultaneous removal of tetracycline and its related antibiotic resistance bacteria and genes by ferrate(VI)." Science of The Total Environment 786, no. : 147492.

Journal article
Published: 15 December 2020 in Water Research
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Biological activated carbon (BAC) filtration, a process widely used in drinking water treatment, was recently reported to harbor antibiotic resistance genes (ARGs). This emerging contamination is poorly understood. This study was conducted to investigate the occurrence of ARGs and bacterial community in full-scale BAC filters during the backwash cycle using high-throughput qPCR and high-throughput sequencing. A total of 178 ARGs were detected in all biofilm samples, with relative abundance ranging from 0.1 to 1.37 copies per 16S rRNA and absolute abundance ranging from 4.48 × 107 to 3.09 × 109 copies/g carbon. Biofilms sampled from different filters shared most detected ARGs and dominant genera including Bryobacter, Pedomicrobium, Reyranella, and Terrimonas, though their bacterial community structure differed significantly. After backwashing, the relative ARGs abundance increased by 1.5- to 3.8-folds and the absolute ARGs abundance increased by 0.90- to 1.12-logs in all biofilm samples during filter ripening, indicating that ARGs accumulated in filters during this period. Redundancy analysis suggested that such ARGs accumulation was mainly driven by horizontal gene transfer in winter, but highly correlated with the increasing relative abundance of genera Bryobacter and Acidibacter in summer. It was observed that 80.6 %-89.3% of the detected ARGs persisted in the filters despite of the backwashing. Given the high richness and relative abundance of ARGs in BAC filter and the ineffectiveness of backwashing in ARG removal, more stringent downstream disinfection strategies are deserved and more research is necessary to assess potential human health risks due to the persistence of ARGs in drinking water.

ACS Style

Kun Wan; Lizheng Guo; Chengsong Ye; Jianwen Zhu; Menglu Zhang; Xin Yu. Accumulation of antibiotic resistance genes in full-scale drinking water biological activated carbon (BAC) filters during backwash cycles. Water Research 2020, 190, 116744 .

AMA Style

Kun Wan, Lizheng Guo, Chengsong Ye, Jianwen Zhu, Menglu Zhang, Xin Yu. Accumulation of antibiotic resistance genes in full-scale drinking water biological activated carbon (BAC) filters during backwash cycles. Water Research. 2020; 190 ():116744.

Chicago/Turabian Style

Kun Wan; Lizheng Guo; Chengsong Ye; Jianwen Zhu; Menglu Zhang; Xin Yu. 2020. "Accumulation of antibiotic resistance genes in full-scale drinking water biological activated carbon (BAC) filters during backwash cycles." Water Research 190, no. : 116744.

Journal article
Published: 20 October 2020 in Journal of Hazardous Materials
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Viable but non-culturable (VBNC) bacteria have attracted widespread attention since they are inherently undetected by traditional culture-dependent methods. Importantly, VBNC bacteria could resuscitate under favorable conditions leading to significant public health concerns. Although the total number of viable bacteria has been theorized to be far greater than those that can be cultured, there have been no reports quantifying VBNC pathogenic bacteria in full-scale drinking water treatment plants (DWTPs). In this work, we used both culture-dependent and quantitative PCR combination with propidium monoazide (PMA) dye approaches to characterize cellular viability. Further, we established a method to quantify viable pathogens by relating specific gene copies to viable cell numbers. Ratios of culturable bacteria to viable 16S rRNA gene copies in water and biological activated carbon (BAC) biofilms were 0–4.75% and 0.04–56.24%, respectively. The VBNC E. coli, E. faecalis, P. aeruginosa, Salmonella sp., and Shigella sp. were detected at levels of 0–103 cells/100 mL in source water, 0–102 cells/100 mL in chlorinated water, and 0–103 cells/g in BAC biofilms. In addition, differences between the total and viable community structures after ozonation and chlorination were investigated. The relative abundance of opportunistic pathogens such as Mycobacterium, Sphingomonas, etc. increased in final water, likely due to their chlorine resistance. In summary, we detected significant quantities of viable/VBNC opportunistic pathogens in full-scale DWTPs, confirming that traditional, culture-dependent methods are inadequate for detecting VBNC bacteria. These findings suggest a need to develop and implement rapid, accurate methods for the detection of VBNC pathogenic bacteria in DWTPs to ensure the safety of drinking water.

ACS Style

Lizheng Guo; Kun Wan; Jianwen Zhu; Chengsong Ye; Kassim Chabi; Xin Yu. Detection and distribution of vbnc/viable pathogenic bacteria in full-scale drinking water treatment plants. Journal of Hazardous Materials 2020, 406, 124335 .

AMA Style

Lizheng Guo, Kun Wan, Jianwen Zhu, Chengsong Ye, Kassim Chabi, Xin Yu. Detection and distribution of vbnc/viable pathogenic bacteria in full-scale drinking water treatment plants. Journal of Hazardous Materials. 2020; 406 ():124335.

Chicago/Turabian Style

Lizheng Guo; Kun Wan; Jianwen Zhu; Chengsong Ye; Kassim Chabi; Xin Yu. 2020. "Detection and distribution of vbnc/viable pathogenic bacteria in full-scale drinking water treatment plants." Journal of Hazardous Materials 406, no. : 124335.

Journal article
Published: 29 July 2020 in Water Supply
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Ammonium pollution of source water has become a challenge in rural water supply. Biological roughing filtration combining with low energy consumption and simple operation would be a potential solution to this issue. This study was conducted to investigate ammonium removal by biological up-flow roughing filter packed with ceramic media. Low flow rate did affect the ammonium removal and higher flow rate was suggested, while intense backwashing only showed a slight impact. At 4 m/h, an average reduction of about 51% was obtained, and NH4+-N effluent concentration could be below 0.5 mg/L within a NH4+-N loading rate of 0.1 kg/(m3·d). Biomass and biological activity assessment were performed as well as microbial community analysis. High abundance of nitrifying bacteria contributed to ammonium removal with Nitrospira and Nitrosomonas accounting for 6.59% and 1.12% of the bacteria community, respectively. In addition, the roughing filter showed high turbidity removal efficiency of about 70%. This study suggested that a biological roughing filter could be employed to help rural drinking water plants adapt to the seasonal change and moderate deterioration of source water quality in terms of ammonium pollution with low-cost and simple operation.

ACS Style

Jie Zeng; Kassim Chabi; Yue Hu; Shenghua Zhang; Xin Yu. Ammonium removal of biological roughing filter for rural drinking water pretreatment. Water Supply 2020, 20, 2768 -2778.

AMA Style

Jie Zeng, Kassim Chabi, Yue Hu, Shenghua Zhang, Xin Yu. Ammonium removal of biological roughing filter for rural drinking water pretreatment. Water Supply. 2020; 20 (7):2768-2778.

Chicago/Turabian Style

Jie Zeng; Kassim Chabi; Yue Hu; Shenghua Zhang; Xin Yu. 2020. "Ammonium removal of biological roughing filter for rural drinking water pretreatment." Water Supply 20, no. 7: 2768-2778.

Journal article
Published: 26 May 2020 in Water Supply
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People in remote areas are still drinking surface water that may contain certain pollutants including harmful microorganisms and chemical compounds directly without any pretreatment. In this study, we have designed and operated a pilot-scale drinking water treatment unit as part of our aim to find an economic and easily operable technology for providing drinking water to people in those areas. Our small-scale treatment unit contains filtration and disinfection (UV–C irradiation) stages to remove pollutants from source water. The water quality index was determined based on various parameters such as pH, temperature, dissolved oxygen, nitrate, nitrite, ammonium, phosphorus, dissolved organic carbon and bacteria. Water and media samples after DNA extraction were sequenced using Illumina Miseq throughput sequencing for the determination of bacterial community composition. After the raw water treatment, the reduction of bacteria concentration ranged from 1 to 2 log10. The average removal of the turbidity, ammonium, nitrite, phosphorus and dissolved organic carbon reached up to 95.33%, 85.71%, 100%, 28.57%, and 45%, respectively. In conclusion, multiple biological stages in our designed unit showed an improvement of the drinking water quality. The designed drinking treatment unit produces potable water meeting standards at a lower cost of operation and it can be used in remote areas.

ACS Style

Kassim Chabi; Jie Zeng; Lizheng Guo; Xi Li; Chengsong Ye; Xin Yu. Small-scale drinking water treatment unit of filtration and UV disinfection for remote area. Water Supply 2020, 20, 1 .

AMA Style

Kassim Chabi, Jie Zeng, Lizheng Guo, Xi Li, Chengsong Ye, Xin Yu. Small-scale drinking water treatment unit of filtration and UV disinfection for remote area. Water Supply. 2020; 20 (6):1.

Chicago/Turabian Style

Kassim Chabi; Jie Zeng; Lizheng Guo; Xi Li; Chengsong Ye; Xin Yu. 2020. "Small-scale drinking water treatment unit of filtration and UV disinfection for remote area." Water Supply 20, no. 6: 1.

Journal article
Published: 07 May 2020 in Chemical Engineering Journal
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Toxic cyanobacterial blooms in source waters could impair drinking water quality and chlorine was a common oxidant to treat cyanobacteria in drinking water treatment plants. In natural freshwaters, cyanobacterial bloom is a successive process, mainly including development and maintenance stage. However, previous studies only focused on one stage of cyanobacteria. Here, we collected Microcystis of both stages in lab-scale. Then, cellular characteristics and associated effects of chlorination on cell inactivation, toxin fate of both stages was compared. Results showed Microcystis of both stages remained high photosynthetic capacity, but maintenance stage exhibited higher cell-density and extracellular organic matters, leading to lower chlorination exposure with the same initial dosage of chlorine. However, Microcystis of both stages could be completely inactivated via disrupting membrane integrity, and Microcystis at maintenance stage was less resistant to chlorine attack attributed to poor cellular surfaces. Membrane destruction resulted in the complete release of intracellular toxin for both stages, but with sufficient chlorination exposure, there was no increase of extracellular toxin attributed to faster extracellular toxin degradation than intracellular toxin release. Besides, due to elevated toxin degradation efficiency via chlorination at maintenance stage, its initial higher total toxin could be degraded to below detection limits with lower ct value of 21 mg min L−1 than development stage (30 mg min L−1). These results suggested chlorination could be a feasible option to treat cyanobacteria-laden waters at development and maintenance stage of a successive bloom.

ACS Style

Xi Li; Sheng Chen; Jie Zeng; Kassim Chabi; Weijun Song; Xuanxuan Xian; Xin Yu. Impact of chlorination on cell inactivation, toxin release and degradation of cyanobacteria of development and maintenance stage. Chemical Engineering Journal 2020, 397, 125378 .

AMA Style

Xi Li, Sheng Chen, Jie Zeng, Kassim Chabi, Weijun Song, Xuanxuan Xian, Xin Yu. Impact of chlorination on cell inactivation, toxin release and degradation of cyanobacteria of development and maintenance stage. Chemical Engineering Journal. 2020; 397 ():125378.

Chicago/Turabian Style

Xi Li; Sheng Chen; Jie Zeng; Kassim Chabi; Weijun Song; Xuanxuan Xian; Xin Yu. 2020. "Impact of chlorination on cell inactivation, toxin release and degradation of cyanobacteria of development and maintenance stage." Chemical Engineering Journal 397, no. : 125378.

Journal article
Published: 02 April 2020 in Water Research
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Occurrence of toxic cyanobacterial blooms in natural freshwaters could impair drinking water quality. Chlorine was often employed as an oxidant to treat algal-laden source waters in drinking water treatment plants. However, previous studies only focused on high-viability cyanobacteria at exponential phase. Whether the change of cell-viability of cyanobacteria could affect chlorination was unknown. Here, high- and low-viability Microcystis were collected from a whole life cycle of cyanobacteria in lab-scale, and effects of chlorination on membrane integrity and toxin fate of high- and low-viability Microcystis were subsequently investigated. Results showed chlorine exposure was lower for low-viability cells than high-viability cells with the same initial chlorine dosage, but low-viability cells were less resistant to chlorination, leading to higher rate of membrane damage (kloss) and intracellular toxin release (ki). For high-viability cells, there was no increase of extracellular toxin with sufficient chlorine exposure whereas it showed a continuous increase for low-viability cells mainly due to its lower rate of extracellular toxin degradation (ke, 26 ± 8 M−1 s−1) than intracellular toxin release (ki, 110 ± 16 M−1 s−1) (ke < ki). Besides, total toxin could be completely oxidized for high-viability cells with sufficient chlorine exposure (>30 mg min L−1) whereas chlorination could not work well for low-viability cells even with chlorine exposure of as high as 36 mg min L−1. These findings indicated chlorination may not be a feasible option to treat low-viability cyanobacteria during decline stage of cyanobacterial blooms.

ACS Style

Xi Li; Sheng Chen; Jie Zeng; Weijun Song; Xin Yu. Comparing the effects of chlorination on membrane integrity and toxin fate of high- and low-viability cyanobacteria. Water Research 2020, 177, 115769 .

AMA Style

Xi Li, Sheng Chen, Jie Zeng, Weijun Song, Xin Yu. Comparing the effects of chlorination on membrane integrity and toxin fate of high- and low-viability cyanobacteria. Water Research. 2020; 177 ():115769.

Chicago/Turabian Style

Xi Li; Sheng Chen; Jie Zeng; Weijun Song; Xin Yu. 2020. "Comparing the effects of chlorination on membrane integrity and toxin fate of high- and low-viability cyanobacteria." Water Research 177, no. : 115769.

Environmental biotechnology
Published: 19 March 2020 in Applied Microbiology and Biotechnology
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Household water purifiers are increasingly used to treat drinking water at the household level, but their influence on the microbiological safety of drinking water has rarely been assessed. In this study, representative purifiers, based on different filtering processes, were analyzed for their impact on effluent water quality. The results showed that purifiers reduced chemical qualities such as turbidity and free chlorine. However, a high level of bacteria (102-106 CFU/g) was detected at each stage of filtration using a traditional culture-dependent method, whereas quantitative PCR with propidium monoazide (PMA) treatment showed 106-108 copies/L of total viable bacteria in effluent water, indicating elevated microbial contaminants after purifiers. In addition, high-throughput sequencing revealed a diverse microbial community in effluents and membranes. Proteobacteria (22.06-97.42%) was the dominant phylum found in all samples, except for purifier B, in which Melainabacteria was most abundant (65.79%). For waterborne pathogens, Escherichia coli (100-106 copies/g) and Pseudomonas aeruginosa (100-105 copies/g) were frequently detected by qPCR. Sequencing also demonstrated the presence of E. coli (0-6.26%), Mycobacterium mucogenicum (0.01-3.46%), and P. aeruginosa (0-0.16%) in purifiers. These finding suggest that water from commonly used household purifiers still impose microbial risks to human health.

ACS Style

Wenfang Lin; Chengsong Ye; Lizheng Guo; Dong Hu; Xin Yu. Analysis of microbial contamination of household water purifiers. Applied Microbiology and Biotechnology 2020, 104, 4533 -4545.

AMA Style

Wenfang Lin, Chengsong Ye, Lizheng Guo, Dong Hu, Xin Yu. Analysis of microbial contamination of household water purifiers. Applied Microbiology and Biotechnology. 2020; 104 (10):4533-4545.

Chicago/Turabian Style

Wenfang Lin; Chengsong Ye; Lizheng Guo; Dong Hu; Xin Yu. 2020. "Analysis of microbial contamination of household water purifiers." Applied Microbiology and Biotechnology 104, no. 10: 4533-4545.

Journal article
Published: 16 March 2020 in Chemosphere
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Emerging contaminants such as antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs) are becoming a global environmental problem. In this study, the glow discharge plasma (GDP) was applied for degrading antibiotic resistant Escherichia coli (E. coli) with resistance genes (tetA, tetR, aphA) and transposase gene (tnpA) in 0.9% sterile saline. The results showed that GDP was able to inactivate the antibiotic resistant E. coli and remove the ARGs and reduce the risk of gene transfer. The levels of E. coli determined by 16S rRNA decreased by approximately 4.7 logs with 15 min of discharge treatment. Propidium monoazide - quantitative polymerase chain reaction (PMA-qPCR) tests demonstrated that the cellular structure of 4.8 more logs E. coli was destroyed in 15 min. The reduction of tetA, tetR, aphA, tnpA genes was increased to 5.8, 5.4, 5.3 and 5.5 logs with 30 min discharge treatment, respectively. The removal of ARGs from high salinity wastewater was also investigated. The total abundance of ARGs was reduced by 3.9 logs in 30 min. Scavenging tests indicated that hydroxyl radicals (·OH) was the most probable agents for bacteria inactivation and ARGs degradation. In addition, the active chlorine (Cl· and Cl2) which formed during the discharge may also contribute to the inactivation and degradation.

ACS Style

Ye Yang; Kun Wan; Zhipeng Yang; Dailin Li; Guoxin Li; Songlin Zhang; Lei Wang; Xin Yu. Inactivation of antibiotic resistant Escherichia coli and degradation of its resistance genes by glow discharge plasma in an aqueous solution. Chemosphere 2020, 252, 126476 .

AMA Style

Ye Yang, Kun Wan, Zhipeng Yang, Dailin Li, Guoxin Li, Songlin Zhang, Lei Wang, Xin Yu. Inactivation of antibiotic resistant Escherichia coli and degradation of its resistance genes by glow discharge plasma in an aqueous solution. Chemosphere. 2020; 252 ():126476.

Chicago/Turabian Style

Ye Yang; Kun Wan; Zhipeng Yang; Dailin Li; Guoxin Li; Songlin Zhang; Lei Wang; Xin Yu. 2020. "Inactivation of antibiotic resistant Escherichia coli and degradation of its resistance genes by glow discharge plasma in an aqueous solution." Chemosphere 252, no. : 126476.

Journal article
Published: 06 February 2020 in Scientific Reports
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Escherichia coli is an important pathogenic indicator in drinking water. Viable but non-culturable (VBNC) E. coli induced by low level chlorination was found to have higher antibiotic tolerance. The emerging of VBNC bacteria in drinking water systems is posing challenges to the control of bio-safety. It is necessary to study the underlying mechanisms of VBNC state E. coli under actual residual chlorine condition of drinking water pipe network. In this study, we investigated the changes of morphology and gene expressions that might present such state. The results indicated that the size of VBNC E. coli was not remarkably changed or recovered culturability under favorable environmental conditions. Results from transcriptomic analysis revealed that the regulated genes related to fimbrial-like adhesin protein, putative periplasmic pilin chaperone, regulators of the transcriptional regulation, antibiotic resistance genes and stress-induced genes, rendering VBNC cells more tolerant to adverse environmental conditions. In total of 16 genes were significantly up-regulated under the VBNC state, including three genes encoding toxic protein (ygeG, ibsD, shoB), indicating that VBNC E. coil was still a threat to human. The work is of great relevance in the context of better understanding this poorly understood physiological state.

ACS Style

Chengsong Ye; Huirong Lin; Menglu Zhang; Sheng Chen; Xin Yu. Characterization and potential mechanisms of highly antibiotic tolerant VBNC Escherichia coli induced by low level chlorination. Scientific Reports 2020, 10, 1957 -11.

AMA Style

Chengsong Ye, Huirong Lin, Menglu Zhang, Sheng Chen, Xin Yu. Characterization and potential mechanisms of highly antibiotic tolerant VBNC Escherichia coli induced by low level chlorination. Scientific Reports. 2020; 10 (1):1957-11.

Chicago/Turabian Style

Chengsong Ye; Huirong Lin; Menglu Zhang; Sheng Chen; Xin Yu. 2020. "Characterization and potential mechanisms of highly antibiotic tolerant VBNC Escherichia coli induced by low level chlorination." Scientific Reports 10, no. 1: 1957-11.

Journal article
Published: 30 November 2019 in Environment International
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Frequent heavy-metal pollution accidents severely deteriorated the source water quality of drinking water treatment plants (DWTP). Limited data have explicitly addressed the impact of these incidents on bacterial antibiotic resistance (BAR). In present study, we investigated the shift of antibiotic resistome caused by heavy metal pollution incidents via simulating an arsenic shock loading [As (III)], along with the associated risks imposed on drinking water systems. The results indicated that a quick co-selection of antibiotic resistant bacteria (ARB) was achieved after exposure to 0.2–1 mg/L As (III) for only 6 h, meanwhile, there was an increase of relative abundance of antibiotic resistance genes (ARGs) and mobile genetic elements. Most of the co-selected BAR could be maintained for at least 4 days in the absence of As (III) and antibiotics, implying that the pollution in source water possibly contributed to the preservation and proliferation of antibiotic resistance determinants in the subsequent DWTP. Bacterial community structure analysis showed a strong correlation between bacterial community shift and BAR promotion, and enrichment of opportunistic bacteria (e.g. Escherichia-Shigella, Empedobacter sp. and Elizabethkingia sp.). The results indicated a potential epidemiological threat to the public due to accident-level arsenic contamination in the source water. This study gave insight into understanding the source water pollution accidents from the perspective of bio-hazard and biological risks, and highlighted a neglected important source of BAR in drinking water systems.

ACS Style

Menglu Zhang; Kun Wan; Jie Zeng; Wenfang Lin; Chengsong Ye; Xin Yu. Co-selection and stability of bacterial antibiotic resistance by arsenic pollution accidents in source water. Environment International 2019, 135, 105351 .

AMA Style

Menglu Zhang, Kun Wan, Jie Zeng, Wenfang Lin, Chengsong Ye, Xin Yu. Co-selection and stability of bacterial antibiotic resistance by arsenic pollution accidents in source water. Environment International. 2019; 135 ():105351.

Chicago/Turabian Style

Menglu Zhang; Kun Wan; Jie Zeng; Wenfang Lin; Chengsong Ye; Xin Yu. 2019. "Co-selection and stability of bacterial antibiotic resistance by arsenic pollution accidents in source water." Environment International 135, no. : 105351.

Journal article
Published: 06 September 2019 in Chemosphere
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Disinfection by-products (DBPs) play a significant role in human health. Identification of the precursor of DBPs, which constitutes dissolved organic matter (DOM), can help optimize the processes in a drinking water treatment plant (DWTP). This is very important for obtaining more safe water. In this context, a one-year study was performed in a DWTP. Fluorescence spectra of DOM were quantified for determining DOM composition and properties, and the corresponding DBPs formation was analyzed. Hydrophobic neutral and acidic compounds were found to be the two predominant substances forming DBPs, which also were dominant in the DOM. Coagulation and sedimentation were not effective in DOM elimination. Besides, sand filtration caused organic compounds to increase by 14.8% on average, especially 28.59% for aromatic protein II and 18.7% for soluble microbial product-like compounds, which was due to metabolism by microorganisms present in the filter. Carbonaceous DBPs were elevated from 34.8 μg/L in source water to 42.5 μg/L in effluent, along with organic compounds increasing in filtration, and nitrogenous DBPs were under detection in winter. All DBPs appeared at a high level in summer. Accordingly, enhanced coagulation process and measures that can avoid the release of organic compounds during filtration have been suggested. As the source water was rarely affected by human activities in the study area and owing to the wide use of traditional treatment process, the data of this research can be regarded as environmental background values and the results are considered as a significant reference.

ACS Style

Zihong Fan; Hailing Yang; Shuangfei Li; Xin Yu. Tracking and analysis of DBP precursors’ properties by fluorescence spectrometry of dissolved organic matter. Chemosphere 2019, 239, 124790 .

AMA Style

Zihong Fan, Hailing Yang, Shuangfei Li, Xin Yu. Tracking and analysis of DBP precursors’ properties by fluorescence spectrometry of dissolved organic matter. Chemosphere. 2019; 239 ():124790.

Chicago/Turabian Style

Zihong Fan; Hailing Yang; Shuangfei Li; Xin Yu. 2019. "Tracking and analysis of DBP precursors’ properties by fluorescence spectrometry of dissolved organic matter." Chemosphere 239, no. : 124790.

Journal article
Published: 01 September 2019 in Journal of Microbiological Methods
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RNA-based molecular technique (RT-qPCR) is a promising method for microcystin monitoring in lakes and reservoirs, but great lability of RNA in cyanobacterial samples limits its application. To date, no studies have investigated how to effectively preserve RNA in cyanobacterial samples. In this study, four different treatments (-80 °C freezer, -196 °C liquid nitrogen, 4 °C or 25 °C preservation after adding RNA protective fluid) were employed to preserve RNA in pure culture and field Microcystis samples, and RNA degradation in these treatments were systematically evaluated. Results showed liquid nitrogen was the most effective treatment to preserve RNA in pure culture and field Microcystis samples. RNA preservation using RNA protective fluid was temperature dependent. Low temperature (4 °C) could effectively slow down RNA degradation within a short time (1-7 d), since decay rate of mcyH mRNA (k = 0.00094 d-1) was much lower at 4 °C than that at 25 °C (0.0549 d-1) (P < 0.05). However, for field samples, RNA degradation was much faster than pure culture samples with the same treatment. Therefore, to better preserve RNA in field samples, a practical strategy for RNA preservation combining RNA protective fluid and liquid nitrogen, was proposed. Tests of field experiments showed it was more effective than individual treatment for RNA preservation in Microcystis samples during field sampling. Thus, this strategy could be employed to preserve RNA in cyanobacterial samples during field sampling, which will contribute to the application of RT-qPCR technique for microcystin monitoring in lakes and reservoirs.

ACS Style

Xi Li; Donghua Qiu; Sheng Chen; Jinmei Li; Chao Luo; Dong Hu; Jingjing Li; Jianwen Zhu; Hui Chen; Shuai Li; Xin Yu. Evaluation of RNA degradation in pure culture and field Microcystis samples preserved with various treatments. Journal of Microbiological Methods 2019, 164, 105684 .

AMA Style

Xi Li, Donghua Qiu, Sheng Chen, Jinmei Li, Chao Luo, Dong Hu, Jingjing Li, Jianwen Zhu, Hui Chen, Shuai Li, Xin Yu. Evaluation of RNA degradation in pure culture and field Microcystis samples preserved with various treatments. Journal of Microbiological Methods. 2019; 164 ():105684.

Chicago/Turabian Style

Xi Li; Donghua Qiu; Sheng Chen; Jinmei Li; Chao Luo; Dong Hu; Jingjing Li; Jianwen Zhu; Hui Chen; Shuai Li; Xin Yu. 2019. "Evaluation of RNA degradation in pure culture and field Microcystis samples preserved with various treatments." Journal of Microbiological Methods 164, no. : 105684.

Original article
Published: 07 August 2019 in Folia Microbiologica
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Microbial contamination poses a great threat to aviation system security through mechanisms such as microbiologically influenced corrosion (MIC), fuel filter clogging, and fuel deterioration. In this study, a survey of microbial contamination in aviation fuel obtained from aircraft fuel tanks was performed to test the relationship between microbial contamination and aircraft service life. The contaminating microorganisms were counted, isolated, identified, and subjected to preliminary characterization. A low risk of microbial contamination in the selected samples was confirmed, and there was no significant difference in the counts between culturable bacteria and fungi (p > 0.05). Phylogenetic analysis tree indicated that the diversity of culturable microorganisms was rather low, with 17 bacterial isolates belonging to 13 genera and 12 fungal isolates belonging to 5 genera. No yeast was isolated. The growth characteristics of these isolates indicated that the aircraft fuel tanks harbored various microorganisms that were able to utilize the aviation fuel as a source of carbon and energy. Meanwhile, some isolates caused emulsification and produced acid. The conclusions of this study were that various hazardous microorganisms can root in aircraft aviation fuel tanks. There was no relationship between microbial contamination and aircraft service life (p > 0.05), and continuous good maintenance suppressed microbial proliferation.

ACS Style

Dong Hu; Jie Zeng; Shangshu Wu; Xi Li; Chengsong Ye; Wenfang Lin; Xin Yu. A survey of microbial contamination in aviation fuel from aircraft fuel tanks. Folia Microbiologica 2019, 65, 371 -380.

AMA Style

Dong Hu, Jie Zeng, Shangshu Wu, Xi Li, Chengsong Ye, Wenfang Lin, Xin Yu. A survey of microbial contamination in aviation fuel from aircraft fuel tanks. Folia Microbiologica. 2019; 65 (2):371-380.

Chicago/Turabian Style

Dong Hu; Jie Zeng; Shangshu Wu; Xi Li; Chengsong Ye; Wenfang Lin; Xin Yu. 2019. "A survey of microbial contamination in aviation fuel from aircraft fuel tanks." Folia Microbiologica 65, no. 2: 371-380.

Journal article
Published: 25 July 2019 in Harmful Algae
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Toxic cyanobacterial blooms, occurring frequently worldwide, have posed serious threats to human health and aquatic ecosystem. RNA-based quantitative PCR, which could detect potential toxin-producing cyanobacteria that are actively transcribing toxin genes, is a more reliable method, compared to DNA-based qPCR. However, single-stranded mRNA is labile, and their degradation may lead to an underestimate of gene expression level, even misleading toxic risk management, and thus impeding its application. Here, the mRNA stability of microcystin synthetase genes (mcyA-J) was systematically evaluated in unicellular and colonial Microcystis with various treatments (−80 ℃, −196 ℃, 4 °C or 25 °C with RNases inhibitors). Results revealed the highly instability of toxin gene transcripts, affected by transcript structures and cell aggregation. The −196 ℃ treatment was the most effective for stabilizing these transcripts. RNAstore® (4 °C) could stabilize these transcripts effectively for a short time (less than 7 d), but their stability was strikingly reduced in colonial Microcystis. Furthermore, decay kinetics of mcyA-J transcripts in various treatments was developed, and showed that their decay rates were varied (0.0018–3.014 d−1), due to different molecular structures. The mcyH transcripts had the lowest decay rate (0.0018 d−1 at −196 ℃), attributed to the fewest AU sites and stem-loops involved in its secondary structure. Thus, mcyH was the most proper target gene for monitoring toxic cyanobacterial bloom. These findings provided new insight into mRNA stability of toxin genes, and contributed to monitoring toxic cyanobacterial blooms and water managements using RNA-based molecular techniques.

ACS Style

Xi Li; Donghua Qiu; Sheng Chen; Chao Luo; Dong Hu; Jie Zeng; Hui Chen; Shuai Li; Xin Yu. Importance of messenger RNA stability of toxin synthetase genes for monitoring toxic cyanobacterial bloom. Harmful Algae 2019, 88, 101642 .

AMA Style

Xi Li, Donghua Qiu, Sheng Chen, Chao Luo, Dong Hu, Jie Zeng, Hui Chen, Shuai Li, Xin Yu. Importance of messenger RNA stability of toxin synthetase genes for monitoring toxic cyanobacterial bloom. Harmful Algae. 2019; 88 ():101642.

Chicago/Turabian Style

Xi Li; Donghua Qiu; Sheng Chen; Chao Luo; Dong Hu; Jie Zeng; Hui Chen; Shuai Li; Xin Yu. 2019. "Importance of messenger RNA stability of toxin synthetase genes for monitoring toxic cyanobacterial bloom." Harmful Algae 88, no. : 101642.

Preface
Published: 25 June 2019 in Frontiers of Environmental Science & Engineering
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ACS Style

Xin Yu; Virender K. Sharma; Hui Li. Environmental Antibiotics and Antibiotic Resistance: From Problems to Solutions. Frontiers of Environmental Science & Engineering 2019, 13, 47 .

AMA Style

Xin Yu, Virender K. Sharma, Hui Li. Environmental Antibiotics and Antibiotic Resistance: From Problems to Solutions. Frontiers of Environmental Science & Engineering. 2019; 13 (3):47.

Chicago/Turabian Style

Xin Yu; Virender K. Sharma; Hui Li. 2019. "Environmental Antibiotics and Antibiotic Resistance: From Problems to Solutions." Frontiers of Environmental Science & Engineering 13, no. 3: 47.

Journal article
Published: 21 June 2019 in Environment International
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The occurrence of viable but non-culturable (VBNC) bacteria will result in significant underestimation of viable bacterial counts in drinking water. Whereas, much is unknown in characterizing their viability. In this study, two environmental isolates (Aeromonas sp. and Pseudomonas sp.) and two model strains (E. coli and S. aureus) were induced into VBNC state by UV irradiation. Then, their metabolic activity was determined by 5-cyano-2,3-ditolyl tetrazolium chloride combination flow cytometry (CTC-FCM) and D2O-labeled Raman spectroscopy, respectively, at both population and single cell levels. The results showed that almost all strains could enter VBNC state irradiated by ≥ 5 mJ/cm2 UV. When determined by CTC-FCM, the population metabolic activity for each strain did not vary significantly (p > 0.05) unless the UV dose reached 200 mJ/cm2. Their single cell activity spectrum narrowed slightly, as indicated by changes in the standard deviation of the logarithmic normal distribution (σ) of 0.015–0.033. This minute difference suggested the CTC-FCM method was suitable for assessing the essential viability of VBNC bacteria. With respect to Raman method, an obvious dose-response effect was recorded. With the UV dosages increased from 10 to 200 mJ/cm2, the CD/(CD + CH) for the four strains were reduced to between 95.7% and 47.9% of unirradiated controls, depending on strain and UV dose. Meanwhile, the single cellular Raman spectrum showed much more heterogeneously metabolic activity distribution, with some cells even entering metabolic “silence”. Considering the ubiquitous participation of water in biochemical processes, the Raman method was more appropriate in assessing the overall metabolic activity. The above findings can not only be a reference for VBNC mechanism studies, but also have the potential in optimizing disinfection and other bacterial removal processes.

ACS Style

Lizheng Guo; Chengsong Ye; Li Cui; Kun Wan; Sheng Chen; Shenghua Zhang; Xin Yu. Population and single cell metabolic activity of UV-induced VBNC bacteria determined by CTC-FCM and D2O-labeled Raman spectroscopy. Environment International 2019, 130, 104883 .

AMA Style

Lizheng Guo, Chengsong Ye, Li Cui, Kun Wan, Sheng Chen, Shenghua Zhang, Xin Yu. Population and single cell metabolic activity of UV-induced VBNC bacteria determined by CTC-FCM and D2O-labeled Raman spectroscopy. Environment International. 2019; 130 ():104883.

Chicago/Turabian Style

Lizheng Guo; Chengsong Ye; Li Cui; Kun Wan; Sheng Chen; Shenghua Zhang; Xin Yu. 2019. "Population and single cell metabolic activity of UV-induced VBNC bacteria determined by CTC-FCM and D2O-labeled Raman spectroscopy." Environment International 130, no. : 104883.

Articles
Published: 09 May 2019 in Environmental Technology
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Many bacteria, including Escherichia coli, are known to enter into a viable but non-culturable (VBNC) state when exposed to harsh environmental stresses. The VBNC cells introduced by chlorination/chloramination have raised increasing concern about biological safety of drinking water. A quantitative relationship between chlorination/chloramination and number of VBNC cells has not been found. In this study, a mathematical model was developed to quantify the effect of chlorination/chloramination on induction of viable but non-culturable (VBNC) Escherichia coli. the model was generated based on a first order kinetics of chlorination/chloramination using the data collected from laboratory disinfection experiments. The disinfection rates of culturable cells (kc) and viable cells (kv) were dose-dependent, and they were also modelled in different initial concentrations by regression analysis to overcome the shortcoming of dose-dependent. In general, the kc and kv values for chlorination (kc, 2.59–29.89 h-1; kv, 19.52–26.74 h-1) was 2 to 58 times greater than that for chloramination (kc, 0.5446–10.81 h-1; kv, 0.3398–14.57 h-1), suggesting that chlorine was more effective than chloramine in reducing the number of culturable and VBNC cells at same dose of disinfectant. Ultimately, the generated models, which could describe the dynamics of VBNC cells formation in chlorination/chloramination, can provide practical guidance in drinking water treatment and it can also be applied to risk assessment of drinking water management systems.

ACS Style

Sheng Chen; Jie Zeng; Yahong Wang; Chengsong Ye; Shuai Zhu; Lin Feng; Shenghua Zhang; Xin Yu. Modelling the effect of chlorination/chloramination on induction of viable but non-culturable (VBNC) Escherichia coli. Environmental Technology 2019, 41, 3443 -3455.

AMA Style

Sheng Chen, Jie Zeng, Yahong Wang, Chengsong Ye, Shuai Zhu, Lin Feng, Shenghua Zhang, Xin Yu. Modelling the effect of chlorination/chloramination on induction of viable but non-culturable (VBNC) Escherichia coli. Environmental Technology. 2019; 41 (26):3443-3455.

Chicago/Turabian Style

Sheng Chen; Jie Zeng; Yahong Wang; Chengsong Ye; Shuai Zhu; Lin Feng; Shenghua Zhang; Xin Yu. 2019. "Modelling the effect of chlorination/chloramination on induction of viable but non-culturable (VBNC) Escherichia coli." Environmental Technology 41, no. 26: 3443-3455.