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Zhang Z, Zhang H, Wu G, Xu X, Cao R, Wan Q, Xu H, Wang J, Huang T, Wen G. The aggregation characteristics of Aspergillus spores under various conditions and the impact on LPUV inactivation: Comparisons with chlorine-based disinfection. WATER RESEARCH 2024; 253:121323. [PMID: 38377927 DOI: 10.1016/j.watres.2024.121323] [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: 10/21/2023] [Revised: 01/30/2024] [Accepted: 02/14/2024] [Indexed: 02/22/2024]
Abstract
Aggregation is the primary step prior to fungal biofilm development. Understanding the attributes of aggregation is of great significance to better control the emergence of waterborne fungi. In this study, the aggregation of Aspergills spores (A. flavus and A. fumigatus) under various salt, culture medium, and humic acid (HA) conditions was investigated for the first time, and the inactivation via low-pressure ultraviolet (LPUV) upon aggregated Aspergillus spores was also presented. The aggregation efficiency and size of aggregates increased over time and at low salt (NaCl and CaCl2) concentration (10 mM) while decreasing with the continuous increase of salt concentration (100 and 200 mM). Increasing the concentration of culture medium and HA promoted the aggregation of fungal spores. Spores became hydrated, swelled, and secreted more viscous substances during the growth period, which accelerated the aggregation process. Results also suggested that fungal spores aggregated more easily in actual water, posing a high risk of biohazard in real-life scenarios. Inactivation efficiency by LPUV decreased with higher aggregation degrees due to the protection from the damaged spores on the outer layer and the shielding of pigments in the cell wall. Compared to chlorine-based disinfection, the aggregation resulted in the extension of shoulder length yet neglectable change of inactivation rate constant under LPUV treatment. Further investigation of cell membrane integrity and intracellular reactive oxygen species was conducted to elucidate the difference in mechanisms between various techniques. This study provides insight into the understanding and controlling of the aggregation of fungal spores.
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Affiliation(s)
- Zhenghong Zhang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Huan Zhang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Gehui Wu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Xiangqian Xu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Ruihua Cao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Qiqi Wan
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Huining Xu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Jingyi Wang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Tinglin Huang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Gang Wen
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China.
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2
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Zhao X, Wang J, Li D, Ma F, Fang Y, Lu J, Hou N. Investigation of non-classical secretion of oxalate decarboxylase in Bacillus mojavensis XH1 mediated by exopeptide YydF: Mechanism and application. Int J Biol Macromol 2024; 264:130662. [PMID: 38453118 DOI: 10.1016/j.ijbiomac.2024.130662] [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: 09/14/2023] [Revised: 02/20/2024] [Accepted: 03/04/2024] [Indexed: 03/09/2024]
Abstract
Non-classical secretory proteins are widely found in bacteria and have been extensively studied due to their important physiological roles. However, the relevant non-classical secretory mechanisms remain unclear. In this study, we found that oxalate decarboxylase (Bacm OxDC) from Bacillus mojavensis XH1 belongs to non-classical secretory proteins. Its N-terminus showed high hydrophilicity, which was different from the conventional signal peptide. The truncation test revealed that the deletion of the N-terminus affects the structure resulting in its inability to cross the cell membrane. Further studies verified that the exported peptide YydF played an important role in the secretion process of Bacm OxDC. Experimental results on the secretion mechanism indicated that Bacm OxDC bound to the exported peptide YydF and they are translocated to the cell membrane together, after which Bacm OxDC caused cell membrane relaxation for transmembrane secretion. Thereafter, three recombinant proteins were successfully secreted with certain enzymatic activity by fusing Bacm OxDC as a guide protein with various target proteins. To the best of our knowledge, this was the first time that non-classical secretion mechanism in bacteria has been analyzed. The novel discovery may provide a reference and broaden the horizons of the secretion pathway and expression regulation of proteins.
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Affiliation(s)
- Xin Zhao
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China
| | - Jian Wang
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China
| | - Dapeng Li
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China.
| | - Fang Ma
- College of Environment, Harbin Institute of Technology, No. 73 Yellow River Street, Harbin, Heilongjiang 150090, PR China
| | - Yongping Fang
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China
| | - Jia Lu
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China
| | - Ning Hou
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China.
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3
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Zhang J, Tan YM, Li SR, Battini N, Zhang SL, Lin JM, Zhou CH. Discovery of benzopyridone cyanoacetates as new type of potential broad-spectrum antibacterial candidates. Eur J Med Chem 2024; 265:116107. [PMID: 38171147 DOI: 10.1016/j.ejmech.2023.116107] [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: 11/23/2023] [Revised: 12/23/2023] [Accepted: 12/26/2023] [Indexed: 01/05/2024]
Abstract
Unique benzopyridone cyanoacetates (BCs) as new type of promising broad-spectrum antibacterial candidates were discovered with large potential to combat the lethal multidrug-resistant bacterial infections. Many prepared BCs showed broad antibacterial spectrum with low MIC values against the tested strains. Some highly active BCs exhibited rapid sterilization capacity, low resistant trend and good predictive pharmacokinetic properties. Furthermore, the highly active sodium BCs (NaBCs) displayed low hemolysis and cytotoxicity, and especially octyl NaBC 5g also showed in vivo potent anti-infective potential and appreciable pharmacokinetic profiles. A series of preliminary mechanistic explorations indicated that these active BCs could effectively eliminate bacterial biofilm and destroy membrane integrity, thus resulting in the leakage of bacterial cytoplasm. Moreover, their unique structures might further bind to intracellular DNA, DNA gyrase and topoisomerase IV through various direct noncovalent interactions to hinder bacterial reproduction. Meanwhile, the active BCs also induced bacterial oxidative stress and metabolic disturbance, thereby accelerating bacterial apoptosis. These results provided a bright hope for benzopyridone cyanoacetates as potential novel multitargeting broad-spectrum antibacterial candidates to conquer drug resistance.
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Affiliation(s)
- Jing Zhang
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China
| | - Yi-Min Tan
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China
| | - Shu-Rui Li
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China
| | - Narsaiah Battini
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China
| | - Shao-Lin Zhang
- School of Pharmaceutical Sciences, Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Chongqing University, Chongqing, 401331, China.
| | - Jian-Mei Lin
- Department of Infections, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China.
| | - Cheng-He Zhou
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China.
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4
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Cao R, Tan L, Wan Q, Wu G, Wang J, Lin Y, Huang T, Wen G. The improved resistance of germinated spores to ultraviolet irradiation: Comparison with chlorine. CHEMOSPHERE 2024; 349:140929. [PMID: 38092169 DOI: 10.1016/j.chemosphere.2023.140929] [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: 09/19/2023] [Revised: 12/07/2023] [Accepted: 12/07/2023] [Indexed: 12/19/2023]
Abstract
Fungi outbreaks in water will include a series of processes, including spore aggregation, germination, biofilm, and finally present in a mixed state in the aquatic environment. More attention is paid to the control of dispersed fungal spores, however, there was little knowledge of the control of germinated spores. This study investigated the inactivation kinetics and mechanism of ultraviolet (UV) treatment for fungal spores with different germination percentages compared with dormant spores. The results indicated that the inactivation rate constants (k) of spores with 5%-45% germination were 0.0278-0.0299 cm2/mJ for Aspergillus niger and 0.0588-0.0647 cm2/mJ for Penicillium polonicum, which were lower than those of dormant spores. It suggested that germinated spores were more tolerant to UV irradiation than dormant spores, and it may be due to the defensive barrier (upregulated pigments) and some reductive substance (upregulated enoyl reductase) by absorbing UV or reacting with reactive oxygen species according to transcriptome analysis. Compared to dormant spores, the k-UV of germinated spores decreased by 18.17%-26.56% for Aspergillus niger, which was less than k-chlorine (62.33%-69.74%). A slighter decrease in k-UV showed UV irradiation can efficiently control fungi contamination, especially when dormant spores and germinated spores coexisted in actual water systems. This study indicates that more attention should be paid to germinated spores.
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Affiliation(s)
- Ruihua Cao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Lili Tan
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Qiqi Wan
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Gehui Wu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Jingyi Wang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Yingzi Lin
- School of Municipal and Environmental Engineering, Jilin Jianzhu University, Changchun 130118, PR China
| | - Tinglin Huang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Gang Wen
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China.
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5
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Zheng N, Lin X, Huang P, Liu Y, Bartlam M, Wang Y. Tea polyphenols inhibit blooms caused by eukaryotic and prokaryotic algae. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 265:115531. [PMID: 37778238 DOI: 10.1016/j.ecoenv.2023.115531] [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: 06/03/2023] [Revised: 08/31/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
With changes in global climate, blooms are becoming more frequent and difficult to control. Therefore, the selection of algal suppressor agents with effective inhibition and environmental safety is of paramount importance. One of the main treatment strategies is to inhibit the release of harmful algal toxins. Tea polyphenols (TP) are natural products that have been widely used in medicine, the environment, and other fields due to their antibacterial and antioxidant properties. To investigate their potential application in the treatment of algal blooms, TP were applied to three different microalgae. TP exhibited strong inhibitory effects towards all three microalgae. They stimulate the accumulation of ROS in algal cells, leading to lipid peroxidation and subsequent damage to the cell membrane, resulting in the rupture and necrosis of Cyclotella sp. and Chlorella vulgaris cells. Remarkably, it was observed that lower concentrations of TP exhibited the ability to induce apoptosis in M. aeruginosa cells without causing any structural damage. This outcome is particularly significant as it reduces the potential risk of microcystin release resulting from cell rupture. Overall, blooms dominated by different algae can be treated by adjusting the concentration of TP, a new algal suppressor, indicating strong potential treatment applications.
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Affiliation(s)
- Ningning Zheng
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Nankai International Advanced Research Institute (Shenzhen Futian), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Xiaowen Lin
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Nankai International Advanced Research Institute (Shenzhen Futian), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Pan Huang
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Nankai International Advanced Research Institute (Shenzhen Futian), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Yu Liu
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Nankai International Advanced Research Institute (Shenzhen Futian), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Mark Bartlam
- State Key Laboratory of Medicinal Chemical Biology, Nankai International Advanced Research Institute (Shenzhen Futian), College of Life Sciences, Nankai University, Tianjin 300350, China.
| | - Yingying Wang
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Nankai International Advanced Research Institute (Shenzhen Futian), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
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6
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Synergistically enhancing the antibacterial and antibiofilm activities of anion exchange membrane by chemically assembling gentamicin and N-chloramine layers. J Memb Sci 2023. [DOI: 10.1016/j.memsci.2023.121530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
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7
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Wan Q, Wen G, Cui Y, Cao R, Xu X, Wu G, Wang J, Huang T. Occurrence and control of fungi in water: New challenges in biological risk and safety assurance. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 860:160536. [PMID: 36574558 DOI: 10.1016/j.scitotenv.2022.160536] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/03/2022] [Accepted: 11/23/2022] [Indexed: 06/17/2023]
Abstract
Recently, the contamination of fungi in water has aroused widespread concern, which will pose a threat to water quality and safety, and raise diseases risk in the immunocompromised individuals. In this review, the characteristics and different physiological state of fungi in water are summarized. A comprehensive evaluation of the control efficiency and mechanism of waterborne fungi by the commonly used disinfection methods is provided as well. During the disinfection processes of chlorine, chlorine dioxide, chloramine and advanced disinfection processes (ADPs) such as O3-based ADPs and UV-based ADPs, the fungal spores firstly lost their culturability, followed by membrane integrity, and the intracellular reactive oxygen species level increased at the same time, eventually the fungal spores were completely inactivated. The security strategies of drinking water against the contamination of fungi are also discussed in terms of water sources, water treatment plants and pipe network. Finally, future researches need to be explored are proposed: the rapid detection methods, the production laws and control of mycotoxin, and the outbreak conditions of fungi in water. Specifically, exploring efficient, safe and economical technologies, especially ADPs, is still the main direction in the disinfection of fungi in future studies. This review can offer a comprehensive understanding on the occurrence and control of fungi in water to fill the knowledge gap and provide guidance for the future research.
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Affiliation(s)
- Qiqi Wan
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, PR China
| | - Gang Wen
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, PR China; Collaborative Innovation Center of Water Pollution Control and Water Quality Security Assurance of Shaanxi Province, Xi'an University of Architecture and Technology, Xi'an 710055, PR China.
| | - Yuhong Cui
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, No. 1037 Luoyu Road, Hongshan District, Wuhan 430074, PR China
| | - Ruihua Cao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, PR China
| | - Xiangqian Xu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, PR China
| | - Gehui Wu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, PR China
| | - Jingyi Wang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, PR China
| | - Tinglin Huang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, PR China
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8
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Han J, Cao R, Li K, Wang S, Ji G, Xu H, Wang J, Huang T, Wen G. Change of algal organic matter under different dissolved oxygen and pressure conditions and its related disinfection by-products formation potential in metalimnetic oxygen minimum. WATER RESEARCH 2022; 226:119216. [PMID: 36257160 DOI: 10.1016/j.watres.2022.119216] [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: 05/15/2022] [Revised: 08/06/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
Most of the reservoirs or lakes will form a metalimnetic oxygen minimum (MOM) with the characterization of a substantial fraction of dissolved oxygen (DO) depleted below the epilimnion. The effect of intracellular organic matter (IOM) of algal cells transformed under MOM conditions is completely different from that of the original IOM on water quality. In this study, the IOM changes of Microcystic aeruginosa under different MOM conditions and its related disinfection by-products formation potentials (DBPFPs) were investigated by changing the pressure and DO concentration of MOM. Total Fmax increased slightly and then decreased under different pressure conditions, finally decreasing by no more than 22.0%. Under aerobic condition, dissolved organic carbon (DOC) and total Fmax decreased significantly, and decreased by 60.4% and 38.8% within the first 2 days. The results of specific UV absorbance (SUVA) and UV250/UV365 indicated that aromatic compounds and average molecular weight of IOM were gradually increased under different MOM conditions. The total DBPFPs increased firstly and then decreased under different pressure conditions, and finally decreased by 26.2%-33.1%. The decrease of total DBPFPs was significantly higher under aerobic condition than that under anoxic condition, which finally decreased by 64.5%. Redundancy analysis showed that the fluorescence parameter (protein-like and humic-like fluorescence) could be expected as an index to predict the DBPFPs. Moreover, the results revealed that with the decrease of DO, the activity and diversity of natural microbial consortium decreased, which prevented the further degradation and utilization of organic matter by natural microbial consortium. Therefore, lower DO was a key player for the deterioration of water quality under MOM conditions.
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Affiliation(s)
- Jingru Han
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Ruihua Cao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Kai Li
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Shuo Wang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Gang Ji
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Huining Xu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Jingyi Wang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Tinglin Huang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Gang Wen
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China.
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9
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Xu X, Cao R, Li K, Wan Q, Wu G, Lin Y, Huang T, Wen G. The protective role and mechanism of melanin for Aspergillus niger and Aspergillus flavus against chlorine-based disinfectants. WATER RESEARCH 2022; 223:119039. [PMID: 36084430 DOI: 10.1016/j.watres.2022.119039] [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: 07/16/2022] [Revised: 08/20/2022] [Accepted: 08/29/2022] [Indexed: 06/15/2023]
Abstract
Melanin is a critical component of fungal cell wall which protect fungi from adverse environmental tress. However, the role of melanin for fungi during the disinfection with chlorine-based disinfectants has not been elucidated. The results showed that the inactivation rate constants of Aspergillus niger with chlorine and chlorine dioxide decreased from 0.08 to 2.10 min-1 to 0 after addition of 0.32 mg/L melanin. The results indicated addition of extracted fungal melanin inhibited the inactivation efficiency of chlorine and chlorine dioxide. In contrast, the k of Aspergillus niger after inactivation with monochloramine ranged from 1.50 to 1.78 min-1 after addition of melanin which indicated effect of melanin on the inactivation efficiency of monochloramine was negligible. In addition, the extracted fungal melanin exhibited high reactivity with chlorine and chlorine dioxide but very low reactivity with monochloramine. The different inactivation mechanisms of chlorine-based disinfectants and different reactivity of melanin with chlorine-based disinfectants led to the different protective mechanism of melanin for A. niger and A. flavus spores against disinfection with chlorine-based disinfectants. The chlorine and chlorine dioxide appeared to react with functional groups of melanin in cell wall of spores, so sacrificial reactions between melanin and disinfectants decreased the available disinfectants and limited the diffusion of disinfectants to the reactive site on cell membrane, which led to the decrease of the disinfection efficiency for chlorine and chlorine dioxide. The monochloramine could penetrate into cell and damage DNA without the effect of melanin due to its strong penetration and low reactivity with melanin. Our results systematically demonstrate the protective roles of melanin on the fungal spores against chlorine-based disinfectants and the underlying mechanisms in resisting the environmental stress caused by chlorine-based disinfectants, which provides important implications for the control of fungi, especially for fungi producing melanin.
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Affiliation(s)
- Xiangqian Xu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Ruihua Cao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Kai Li
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Qiqi Wan
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Gehui Wu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Yuzhao Lin
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Tinglin Huang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Gang Wen
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
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