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Zheng S, Li J, Yan W, Zhao W, Ye C, Yu X. Biofilm formation and antioxidation were responsible for the increased resistance of N. eutropha to chloramination for drinking water treatment. WATER RESEARCH 2024; 254:121432. [PMID: 38461606 DOI: 10.1016/j.watres.2024.121432] [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: 01/01/2024] [Revised: 03/04/2024] [Accepted: 03/05/2024] [Indexed: 03/12/2024]
Abstract
Chloramination is an effective strategy for eliminating pathogens from drinking water and repressing their regrowth in water distribution systems. However, the inevitable release of NH4+ potentially promotes nitrification and associated ammonia-oxidizing bacteria (AOB) contamination. In this study, AOB (Nitrosomona eutropha) were isolated from environmental water and treated with two disinfection stages (chloramine disinfection and chloramine residues) to investigate the occurrence mechanisms of AOB in chloramination. The results showed that N. eutropha had considerable resistance to monochloramine compared to Escherichia coli, whose inactivation rate constant was 19.4-fold lower. The higher resistance was attributed to high levels of extracellular polymer substances (EPS) in AOB, which contribute to AOB surviving disinfection and entering the distribution system. In AOB response to the chloramine residues stage, the respiratory activity of N. eutropha remained at a high level after three days of continuous exposure to high chloramine residue concentrations (0.5-1.5 mg/L). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) suggested that the mechanism of N. eutropha tolerance involved a significantly high expression of the intracellular oxidative stress-regulating (sodB, txrA) and protein-related (NE1545, NE1546) genes. Additionally, this process enhanced EPS secretion and promoted biofilm formation. Adhesion predictions based on the XDLVO theory corroborated the trend of biofilm formation. Overall, the naturally higher resistance contributed to the survival of AOB in primary disinfection; the enhanced antioxidant response of surviving N. eutropha accompanied by biofilm formation was responsible for their increased resistance to the residual chloramines.
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Affiliation(s)
- Shikan Zheng
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China
| | - Jianguo Li
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China
| | - Wanli Yan
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China
| | - Wenya Zhao
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China
| | - Chengsong Ye
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China.
| | - Xin Yu
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China.
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2
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Pérez-Alfaro JE, Villaseca A, Gaytán R, Martínez-Jardines MA, Buitrón G, Texier AC, Cuervo-López FM. Nitrification activity in the presence of 2-chlorophenol using whole nitrifying cells and cell-free extracts: batch and SBR assays. 3 Biotech 2023; 13:364. [PMID: 37840880 PMCID: PMC10575828 DOI: 10.1007/s13205-023-03764-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 08/29/2023] [Indexed: 10/17/2023] Open
Abstract
Kinetic assays with a nitrifying consortium with whole nitrifying cells amended with 5 mg 2-CP-C/L and 100, 200, 300, or 500 mg NH4+-N/L were carried out in batch and nitrifying sequencing batch reactor (SBR) cultures. No nitrification activity was observed in batch assays with 100 mg NH4+-N/L and 5 mg 2-CP-C/L. Nevertheless, increasing the ammonium concentration from 200 to 500 mg NH4+-N/L allowed simultaneous ammonium and nitrite oxidation even in the presence of 5 mg 2-CP-C/L plus the halogenated compound consumption. Under these conditions, the ammonium monooxygenase enzyme participated in 2-CP consumption. Complete nitrification and simultaneous elimination of 5 mg 2-CP-C/L were achieved in the SBR amended with 200-500 mg NH4+-N/L. The inhibitory effect of 2-CP on the nitrite oxidation process completely disappeared under these conditions. Assays with nitrifying cell-free extracts, ammonium (100 mg NH4+-N/L), and 2-CP (5 mg 2-CP-C/L) were also conducted. In the absence of 2-CP, the nitrifying cell-free extracts maintained up to 60% of the nitrifying activity compared to whole-cells. Contrary to whole-cell assays, cell-free extracts were capable of simultaneously oxidizing ammonium and consuming 2-CP. However, the inhibitory effect of 2-CP on nitrification was still present as lower specific rates of ammonium consumption and nitrate production were obtained. Thus, these assays indicate that the presence of 2-CP affects both, the ammonium transport mechanism and the activity of nitrifying enzymes. Supplementary Information The online version contains supplementary material available at 10.1007/s13205-023-03764-z.
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Affiliation(s)
- J. E. Pérez-Alfaro
- Department of Biotechnology, Universidad Autónoma Metropolitana-Iztapalapa, Iztapalapa, CP 09310 Mexico City, México
| | - A. Villaseca
- Department of Biotechnology, Universidad Autónoma Metropolitana-Iztapalapa, Iztapalapa, CP 09310 Mexico City, México
| | - Raúl Gaytán
- Department of Biotechnology, Universidad Autónoma Metropolitana-Iztapalapa, Iztapalapa, CP 09310 Mexico City, México
| | - M. A. Martínez-Jardines
- Department of Biotechnology, Universidad Autónoma Metropolitana-Iztapalapa, Iztapalapa, CP 09310 Mexico City, México
| | - G. Buitrón
- Unidad Académica del Instituto de Ingeniería, Universidad Nacional Autónoma de México, 76230 Querétaro, Querétaro México
| | - A.-C. Texier
- Department of Biotechnology, Universidad Autónoma Metropolitana-Iztapalapa, Iztapalapa, CP 09310 Mexico City, México
| | - F. M. Cuervo-López
- Department of Biotechnology, Universidad Autónoma Metropolitana-Iztapalapa, Iztapalapa, CP 09310 Mexico City, México
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Liu HH, Yang L, Guo LK, Tu LX, Li XT, Wang J, Ren YX. The nutrient removal and tolerance mechanism of a heterotrophic nitrifying bacterium Pseudomonas putida strain NP5 under metal oxide nanoparticles stress. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:28227-28237. [PMID: 36399297 DOI: 10.1007/s11356-022-24055-9] [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: 05/28/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
The occurrence of metal oxide nanoparticles (NPs) in wastewater treatment plants (WWTPs) has raised great concerns about their adverse impacts on nitrification performance. In this study, a heterotrophic nitrifying bacterium Pseudomonas putida strain NP5 showed strong resistance against TiO2 and NiO NPs. Under 5-50 mg/L NP stress, cell viability was still normal, and the final nutrient removal rates, always higher than 80%, were slightly inhibited. Correspondingly, the PO43--P removal rates were almost the same as those observed in the control test. Although the enzyme assay demonstrated ammonia monooxygenase and hydroxylamine oxidoreductase activities markedly decreased caused by increased reactive oxygen species (ROS) level under 50 mg/L NPs stress. The total antioxidant capability of NP5 could eliminate excess ROS to maintain a balance between oxidants and antioxidants. Besides, in response to the escalating burden of NPs, strain NP5 tended to secrete more extracellular polymeric substances (EPS), which could protect cell from being damaged by binding to ions and coating. Thus, the strong NP resistance of NP5 would help to overcome the vulnerability of the nitrification process in WWTPs.
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Affiliation(s)
- Huan-Huan Liu
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Lei Yang
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
| | - Lin-Kai Guo
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Li-Xin Tu
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Xiao-Tong Li
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Jia Wang
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Yong-Xiang Ren
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China
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Paśmionka IB, Gospodarek J. Assessment of the Impact of Selected Industrial Wastewater on the Nitrification Process in Short-Term Tests. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19053014. [PMID: 35270705 PMCID: PMC8910604 DOI: 10.3390/ijerph19053014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 02/06/2023]
Abstract
Many chemical compounds can inhibit the nitrification process, especially organic compounds used in the chemical industry. This results in a decrease in the nitrification intensity or even a complete termination of this process. As the technological design of the selected municipal and industrial wastewater treatment plant (WWTP) assumed the dephosphation process, without taking into account nitrification, it was necessary to reduce the concentration of ammonium nitrogen in the treated sewage supplied to the Vistula River. Therefore, the aim of the research was to determine the inhibition of nitrification in the activated sludge method under the influence of industrial wastewater from the production of various organic compounds and to select the most toxic wastewater in relation to nitrifiers. The assessment of nitrification inhibition was carried out on the basis of the method of short-term (4-h) impact of the tested sewage on nitrifying bacteria in the activated sludge. The research covered nine different types of chemical sewage, including wastewater from the production of synthetic rubbers, styrene plastics, adhesives, solvents and emulsifiers. The nitrification process was inhibited to the highest degree by wastewater from the production of styrene-butadiene rubbers (72%). Only wastewater from the production of methacrylate (polymethyl methacrylate) had the lowest degree of inhibition: 16%. These wastewaters also have a toxic effect on the entire biocenosis and adversely affect the structure of activated sludge flocs. The attempts to filter toxic wastewater through the ash basins significantly relieved the inhibition of nitrification.
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5
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Canto-Encalada G, Tec-Campos D, Tibocha-Bonilla JD, Zengler K, Zepeda A, Zuñiga C. Flux balance analysis of the ammonia-oxidizing bacterium Nitrosomonas europaea ATCC19718 unravels specific metabolic activities while degrading toxic compounds. PLoS Comput Biol 2022; 18:e1009828. [PMID: 35108266 PMCID: PMC8853641 DOI: 10.1371/journal.pcbi.1009828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 02/17/2022] [Accepted: 01/11/2022] [Indexed: 11/26/2022] Open
Abstract
The ammonia-oxidizing bacterium Nitrosomonas europaea has been widely recognized as an important player in the nitrogen cycle as well as one of the most abundant members in microbial communities for the treatment of industrial or sewage wastewater. Its natural metabolic versatility and extraordinary ability to degrade environmental pollutants (e.g., aromatic hydrocarbons such as benzene and toluene) enable it to thrive under various harsh environmental conditions. Constraint-based metabolic models constructed from genome sequences enable quantitative insight into the central and specialized metabolism within a target organism. These genome-scale models have been utilized to understand, optimize, and design new strategies for improved bioprocesses. Reduced modeling approaches have been used to elucidate Nitrosomonas europaea metabolism at a pathway level. However, genome-scale knowledge about the simultaneous oxidation of ammonia and pollutant metabolism of N. europaea remains limited. Here, we describe the reconstruction, manual curation, and validation of the genome-scale metabolic model for N. europaea, iGC535. This reconstruction is the most accurate metabolic model for a nitrifying organism to date, reaching an average prediction accuracy of over 90% under several growth conditions. The manually curated model can predict phenotypes under chemolithotrophic and chemolithoorganotrophic conditions while oxidating methane and wastewater pollutants. Calculated flux distributions under different trophic conditions show that several key pathways are affected by the type of carbon source available, including central carbon metabolism and energy production. Nitrosomonas europaea catalyzes the first step of the nitrification process (ammonia to nitrite). It has been recognized as one of the most important members of microbial communities of wastewater treatment processes. Genome-scale models are powerful tools in process optimization since they can predict the organism’s behavior under different growth conditions. The final genome-scale model of N. europaea ATCC19718, iGC535, can predict growth and oxygen uptake rates with 90.52% accuracy under chemolithotrophic and chemolitoorganotrophic conditions. Moreover, iGC535 can predict the simultaneous oxidation of ammonia and wastewater pollutants, such as benzene, toluene, phenol and, chlorobenzene. iGC535 represents the most comprehensive knowledge-base for a nitrifying organism available to date. The genome-scale model reconstructed in this work brings us closer to understanding N. europaea’s role in a community with other nitrifying bacteria.
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Affiliation(s)
| | - Diego Tec-Campos
- Facultad de Ingeniería Química, Universidad Autónoma de Yucatán, Mérida, México
- Department of Pediatrics, University of California, San Diego, California, United States of America
| | - Juan D. Tibocha-Bonilla
- Department of Pediatrics, University of California, San Diego, California, United States of America
| | - Karsten Zengler
- Department of Pediatrics, University of California, San Diego, California, United States of America
- Department of Bioengineering, University of California, San Diego, California, United States of America
- Center for Microbiome Innovation, University of California, San Diego, California, United States of America
| | - Alejandro Zepeda
- Facultad de Ingeniería Química, Universidad Autónoma de Yucatán, Mérida, México
| | - Cristal Zuñiga
- Department of Pediatrics, University of California, San Diego, California, United States of America
- * E-mail:
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6
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Zakaria NN, Gomez-Fuentes C, Abdul Khalil K, Convey P, Roslee AFA, Zulkharnain A, Sabri S, Shaharuddin NA, Cárdenas L, Ahmad SA. Statistical Optimisation of Diesel Biodegradation at Low Temperatures by an Antarctic Marine Bacterial Consortium Isolated from Non-Contaminated Seawater. Microorganisms 2021; 9:microorganisms9061213. [PMID: 34205164 PMCID: PMC8227063 DOI: 10.3390/microorganisms9061213] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/28/2021] [Accepted: 05/31/2021] [Indexed: 12/03/2022] Open
Abstract
Hydrocarbon pollution is widespread around the globe and, even in the remoteness of Antarctica, the impacts of hydrocarbons from anthropogenic sources are still apparent. Antarctica’s chronically cold temperatures and other extreme environmental conditions reduce the rates of biological processes, including the biodegradation of pollutants. However, the native Antarctic microbial diversity provides a reservoir of cold-adapted microorganisms, some of which have the potential for biodegradation. This study evaluated the diesel hydrocarbon-degrading ability of a psychrotolerant marine bacterial consortium obtained from the coast of the north-west Antarctic Peninsula. The consortium’s growth conditions were optimised using one-factor-at-a-time (OFAT) and statistical response surface methodology (RSM), which identified optimal growth conditions of pH 8.0, 10 °C, 25 ppt NaCl and 1.5 g/L NH4NO3. The predicted model was highly significant and confirmed that the parameters’ salinity, temperature, nitrogen concentration and initial diesel concentration significantly influenced diesel biodegradation. Using the optimised values generated by RSM, a mass reduction of 12.23 mg/mL from the initial 30.518 mg/mL (4% (w/v)) concentration of diesel was achieved within a 6 d incubation period. This study provides further evidence for the presence of native hydrocarbon-degrading bacteria in non-contaminated Antarctic seawater.
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Affiliation(s)
- Nur Nadhirah Zakaria
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (N.N.Z.); (A.F.A.R.); (N.A.S.)
| | - Claudio Gomez-Fuentes
- Department of Chemical Engineering, Universidad de Magallanes, Avda. Bulnes, Punta Arenas 01855, Región de Magallanes y Antártica Chilena, Chile;
- Center for Research and Antarctic Environmental Monitoring (CIMAA), Universidad de Magallanes, Avda. Bulnes, Punta Arenas 01855, Región de Magallanes y Antártica Chilena, Chile
| | - Khalilah Abdul Khalil
- School of Biology, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia;
| | - Peter Convey
- British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge CB3 0ET, UK;
- Department of Zoology, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa
| | - Ahmad Fareez Ahmad Roslee
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (N.N.Z.); (A.F.A.R.); (N.A.S.)
| | - Azham Zulkharnain
- Department of Bioscience and Engineering, College of Systems Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minumaku, Saitama 337-8570, Japan;
| | - Suriana Sabri
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia;
| | - Noor Azmi Shaharuddin
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (N.N.Z.); (A.F.A.R.); (N.A.S.)
| | - Leyla Cárdenas
- Centro Fondap Ideal, Insituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile;
| | - Siti Aqlima Ahmad
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (N.N.Z.); (A.F.A.R.); (N.A.S.)
- Center for Research and Antarctic Environmental Monitoring (CIMAA), Universidad de Magallanes, Avda. Bulnes, Punta Arenas 01855, Región de Magallanes y Antártica Chilena, Chile
- National Antarctic Research Centre, B303 Level 3, Block B, IPS Building, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- Correspondence:
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7
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Hocinat A, Boudemagh A, Ali-Khodja H, Medjemadj M. Aerobic degradation of BTEX compounds by Streptomyces species isolated from activated sludge and agricultural soils. Arch Microbiol 2020; 202:2481-2492. [PMID: 32617605 DOI: 10.1007/s00203-020-01970-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/28/2020] [Accepted: 06/24/2020] [Indexed: 10/23/2022]
Abstract
In this study, we tested the ability of Streptomyces to use for their growth benzene, toluene, ethylbenzene, and o-, m-, p-xylenes as sole source of carbon and energy. These bacteria were isolated from agricultural soils and activated sludge samples from a wastewater treatment plant. The results show that Streptomyces are capable of degrading at least one of the BTEX compounds. Among them, 3 isolates from activated sludge called (U, F and V) and a single isolate (SA13) isolated from an agricultural soil, can use as the sole source of carbon and energy, all of these BTEX compounds at concentrations of 1500 mg/L. Based on the analysis of the 16S rRNA gene sequence, two active strains were identified as Streptomyces fimicarius, Streptomyces cavourensis, Streptomyces flavogriseus and Streptomyces pratensis. These strains can be excellent candidates for the bioremediation of the telluric and aquatic sites polluted by these xenobiotics.
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Affiliation(s)
- Amira Hocinat
- Faculté Des Sciences de La Nature Et de La Vie, Département de Microbiologie, Université Frères Mentouri-Constantine 1, 25017, Constantine, Algeria
| | - Allaoueddine Boudemagh
- Faculté Des Sciences de La Nature Et de La Vie, Département de Microbiologie, Université Frères Mentouri-Constantine 1, 25017, Constantine, Algeria
| | - Hocine Ali-Khodja
- Laboratoire de Pollution Et de Traitement Des Eaux, Faculté Des Sciences Exactes, Département de Chimie, Université Frères Mentouri-Constantine 1, Constantine, Algeria.
| | - Meissa Medjemadj
- Faculté Des Sciences de La Nature Et de La Vie, Département de Microbiologie, Université Frères Mentouri-Constantine 1, 25017, Constantine, Algeria
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8
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Urakawa H, Rajan S, Feeney ME, Sobecky PA, Mortazavi B. Ecological response of nitrification to oil spills and its impact on the nitrogen cycle. Environ Microbiol 2018; 21:18-33. [DOI: 10.1111/1462-2920.14391] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 08/11/2018] [Accepted: 08/17/2018] [Indexed: 01/01/2023]
Affiliation(s)
- Hidetoshi Urakawa
- Department of Marine and Ecological Sciences Florida Gulf Coast University Fort Myers FL, 33965 USA
| | - Suja Rajan
- Department of Biological Sciences University of Alabama Tuscaloosa AL, 35487 USA
| | - Megan E. Feeney
- Department of Marine and Ecological Sciences Florida Gulf Coast University Fort Myers FL, 33965 USA
| | - Patricia A. Sobecky
- Department of Biological Sciences University of Alabama Tuscaloosa AL, 35487 USA
| | - Behzad Mortazavi
- Department of Biological Sciences University of Alabama Tuscaloosa AL, 35487 USA
- Dauphin Island Sea Lab Dauphin Island AL, 36528 USA
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9
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Barker LK, Giska JR, Radniecki TS, Semprini L. Effects of short- and long-term exposure of silver nanoparticles and silver ions to Nitrosomonas europaea biofilms and planktonic cells. CHEMOSPHERE 2018; 206:606-614. [PMID: 29778938 DOI: 10.1016/j.chemosphere.2018.05.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 04/27/2018] [Accepted: 05/03/2018] [Indexed: 06/08/2023]
Abstract
The increasing use of silver nanoparticles (AgNPs) in consumer products, and their resulting influx into wastewater, may pose a threat to biological nutrient removal in wastewater treatment plants. Planktonic ammonia-oxidizing bacteria (AOB), which convert ammonia to nitrite in the first step of nitrification, are highly sensitive to AgNPs and their released silver ions (Ag+), but the sensitivity of AOB biofilms to AgNPs and Ag+ is less clear. This study demonstrated that biofilms of Nitrosomonas europaea, a model AOB, were more resistant to both short-term and long-term exposure to AgNP and Ag+ than planktonic cells. The increased resistance of N. europaea biofilms was attributed primarily to the increased biomass and slower growth rates present in the biofilm. Similar inhibition mechanisms were observed for AgNPs and Ag+ in both planktonic cells and biofilms with enzymatic inhibition observed at lower concentrations and cell lysis observed at higher concentrations. Long-term continuous exposure to AgNPs lowered the inhibitory concentration by 1-2 orders of magnitude below that required by short-term exposures. Although the total AgNP load was similar between the short and long-term exposure scenarios, the long-term exposure resulted in an order of magnitude more silver being associated in the biofilms and is the primary reason for the increased sensitivity observed. This suggests that short-term batch toxicity assays may greatly underestimate the sensitivity of biofilm treatment systems to long-term exposures of low concentrations of AgNPs and Ag+.
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Affiliation(s)
- L K Barker
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA
| | - J R Giska
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA
| | - T S Radniecki
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA.
| | - L Semprini
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA
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10
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Xu Y, Yuan Z, Ni BJ. Biotransformation of acyclovir by an enriched nitrifying culture. CHEMOSPHERE 2017; 170:25-32. [PMID: 27974268 DOI: 10.1016/j.chemosphere.2016.12.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/02/2016] [Accepted: 12/04/2016] [Indexed: 06/06/2023]
Abstract
This work evaluates the biodegradation of the antiviral drug acyclovir by an enriched nitrifying culture during ammonia oxidation and without the addition of ammonium. The study on kinetics was accompanied with the structural elucidation of biotransformation products through batch biodegradation experiments at two different initial levels of acyclovir (15 mg L-1 and 15 μg L-1). The pseudo first order kinetic studies of acyclovir in the presence of ammonium indicated the higher degradation rates under higher ammonia oxidation rates than those constant degradation rates in the absence of ammonium. The positive correlation was found between acyclovir degradation rate and ammonia oxidation rate, confirming the cometabolism of acyclovir by the enriched nitrifying culture in the presence of ammonium. Formation of the product carboxy-acyclovir (P239) indicated the main biotransformation pathway was aerobic oxidation of the terminal hydroxyl group, which was independent on the metabolic type (i.e. cometabolism or metabolism). This enzyme-linked reaction might be catalyzed by monooxygenase from ammonia oxidizing bacteria or heterotrophs. The formation of carboxy-acyclovir was demonstrated to be irrelevant to the acyclovir concentrations applied, indicating the revealed biotransformation pathway might be the dominant removal pathway of acyclovir in wastewater treatment.
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Affiliation(s)
- Yifeng Xu
- Advanced Water Management Centre, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia
| | - Zhiguo Yuan
- Advanced Water Management Centre, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia
| | - Bing-Jie Ni
- Advanced Water Management Centre, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia.
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11
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Wu J, Lu H, Zhu G, Chen L, Chang Y, Yu R. Regulation of membrane fixation and energy production/conversion for adaptation and recovery of ZnO nanoparticle impacted Nitrosomonas europaea. Appl Microbiol Biotechnol 2017; 101:2953-2965. [DOI: 10.1007/s00253-017-8092-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/09/2016] [Accepted: 12/21/2016] [Indexed: 11/24/2022]
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12
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Kapoor V, Elk M, Li X, Santo Domingo J. Inhibitory effect of cyanide on wastewater nitrification determined using
SOUR
and
RNA
‐based gene‐specific assays. Lett Appl Microbiol 2016; 63:155-61. [DOI: 10.1111/lam.12603] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 11/29/2022]
Affiliation(s)
- V. Kapoor
- Oak Ridge Institute for Science and Education Oak Ridge TN USA
- U.S. Environmental Protection Agency, Office of Research and Development Cincinnati OH USA
| | - M. Elk
- Pegasus Technical Services, Inc. Cincinnati OH USA
| | - X. Li
- Oak Ridge Institute for Science and Education Oak Ridge TN USA
- U.S. Environmental Protection Agency, Office of Research and Development Cincinnati OH USA
| | - J.W. Santo Domingo
- U.S. Environmental Protection Agency, Office of Research and Development Cincinnati OH USA
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13
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Bhaganna P, Bielecka A, Molinari G, Hallsworth JE. Protective role of glycerol against benzene stress: insights from the Pseudomonas putida proteome. Curr Genet 2015; 62:419-29. [PMID: 26612269 DOI: 10.1007/s00294-015-0539-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 11/04/2015] [Accepted: 11/05/2015] [Indexed: 01/09/2023]
Abstract
Chemical activities of hydrophobic substances can determine the windows of environmental conditions over which microbial systems function and the metabolic inhibition of microorganisms by benzene and other hydrophobes can, paradoxically, be reduced by compounds that protect against cellular water stress (Bhaganna et al. in Microb Biotechnol 3:701-716, 2010; Cray et al. in Curr Opin Biotechnol 33:228-259, 2015a). We hypothesized that this protective effect operates at the macromolecule structure-function level and is facilitated, in part at least, by genome-mediated adaptations. Based on proteome profiling of the soil bacterium Pseudomonas putida, we present evidence that (1) benzene induces a chaotrope-stress response, whereas (2) cells cultured in media supplemented with benzene plus glycerol were protected against chaotrope stress. Chaotrope-stress response proteins, such as those involved in lipid and compatible-solute metabolism and removal of reactive oxygen species, were increased by up to 15-fold in benzene-stressed cells relative to those of control cultures (no benzene added). By contrast, cells grown in the presence of benzene + glycerol, even though the latter grew more slowly, exhibited only a weak chaotrope-stress response. These findings provide evidence to support the hypothesis that hydrophobic substances induce a chaotropicity-mediated water stress, that cells respond via genome-mediated adaptations, and that glycerol protects the cell's macromolecular systems. We discuss the possibility of using compatible solutes to mitigate hydrocarbon-induced stresses in lignocellulosic biofuel fermentations and for industrial and environmental applications.
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Affiliation(s)
- Prashanth Bhaganna
- MBC, School of Biological Sciences, Institute for Global Food Security, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland, UK
| | - Agata Bielecka
- Environmental Microbiology Laboratory, Helmholtz Centre for Infection Research, D-38124, Braunschweig, Germany
- Molecular Biology Department, Helmholtz Centre for Infection Research, D-38124, Braunschweig, Germany
| | - Gabriella Molinari
- Environmental Microbiology Laboratory, Helmholtz Centre for Infection Research, D-38124, Braunschweig, Germany
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, D-38124, Braunschweig, Germany
| | - John E Hallsworth
- MBC, School of Biological Sciences, Institute for Global Food Security, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland, UK.
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14
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Kapoor V, Li X, Elk M, Chandran K, Impellitteri CA, Santo Domingo JW. Impact of Heavy Metals on Transcriptional and Physiological Activity of Nitrifying Bacteria. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:13454-62. [PMID: 26501957 DOI: 10.1021/acs.est.5b02748] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Heavy metals can inhibit nitrification, a key process for nitrogen removal in wastewater treatment. The transcriptional responses of amoA, hao, nirK, and norB were measured in conjunction with specific oxygen uptake rate (sOUR) for nitrifying enrichment cultures exposed to different metals (Ni(II), Zn(II), Cd(II), and Pb(II)). There was significant decrease in sOUR with increasing concentrations for Ni(II) (0.03-3 mg/L), Zn(II) (0.1-10 mg/L), and Cd(II) (0.03-1 mg/L) (p < 0.05). However, no considerable changes in sOUR were observed with Pb(II) (1-100 mg/L), except at a dosage of 1000 mg/L causing 84% inhibition. Based on RT-qPCR data, the transcript levels of amoA and hao decreased when exposed to Ni(II) dosages. Slight up-regulation of amoA, hao, and nirK (0.5-1.5-fold) occurred after exposure to 0.3-3 mg/L Zn(II), although their expression decreased for 10 mg/L Zn(II). With the exception of 1000 mg/L Pb(II), stimulation of all genes occurred on Cd(II) and Pb(II) exposure. While overall the results show that RNA-based function-specific assays can be used as potential surrogates for measuring nitrification activity, the degree of inhibition inferred from sOUR and gene transcription is different. We suggest that variations in transcription of functional genes may supplement sOUR based assays as early warning indicators of upsets in nitrification.
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Affiliation(s)
- Vikram Kapoor
- U.S. Environmental Protection Agency, Office of Research and Development, Cincinnati, Ohio 45268, United States
| | - Xuan Li
- U.S. Environmental Protection Agency, Office of Research and Development, Cincinnati, Ohio 45268, United States
| | - Michael Elk
- Pegasus Technical Services, Inc., Cincinnati, Ohio 45268, United States
| | - Kartik Chandran
- Department of Earth and Environmental Engineering, Columbia University , New York, New York 10027, United States
| | - Christopher A Impellitteri
- U.S. Environmental Protection Agency, Office of Research and Development, Cincinnati, Ohio 45268, United States
| | - Jorge W Santo Domingo
- U.S. Environmental Protection Agency, Office of Research and Development, Cincinnati, Ohio 45268, United States
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15
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Lauchnor EG, Semprini L, Wood BD. Kinetic parameter estimation inN. europaeabiofilms using a 2-D reactive transport model. Biotechnol Bioeng 2015; 112:1122-31. [DOI: 10.1002/bit.25527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 08/26/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Ellen G. Lauchnor
- Center for Biofilm Engineering; Montana State University; 366 EPS Bozeman 59717 Montana
| | - Lewis Semprini
- School of Chemical; Biological and Environmental Engineering 102 Gleeson Hall; Oregon State University; Corvallis 97331 Oregon
| | - Brian D. Wood
- School of Chemical; Biological and Environmental Engineering 102 Gleeson Hall; Oregon State University; Corvallis 97331 Oregon
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16
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Wei M, Harnisch F, Vogt C, Ahlheim J, Neu TR, Richnow HH. Harvesting electricity from benzene and ammonium-contaminated groundwater using a microbial fuel cell with an aerated cathode. RSC Adv 2015. [DOI: 10.1039/c4ra12144a] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A microbial fuel cell (MFC) was successfully applied for the treatment of benzene and ammonium co-contaminated groundwater.
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Affiliation(s)
- Manman Wei
- Department of Isotope Biogeochemistry
- Helmholtz Centre for Environmental Research – UFZ
- 04318 Leipzig
- Germany
- Faculty of Natural Sciences
| | - Falk Harnisch
- Department of Environmental Microbiology
- Helmholtz Centre for Environmental Research – UFZ
- 04318 Leipzig
- Germany
| | - Carsten Vogt
- Department of Isotope Biogeochemistry
- Helmholtz Centre for Environmental Research – UFZ
- 04318 Leipzig
- Germany
| | - Jörg Ahlheim
- Department of Groundwater Remediation
- Helmholtz Centre for Environmental Research – UFZ
- 04318 Leipzig
- Germany
| | - Thomas R. Neu
- Department of River Ecology
- Helmholtz Centre for Environmental Research – UFZ
- Magdeburg
- Germany
| | - Hans H. Richnow
- Department of Isotope Biogeochemistry
- Helmholtz Centre for Environmental Research – UFZ
- 04318 Leipzig
- Germany
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17
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Pérez-Alfaro JE, González-Blanco G, Sierra-Palacios E, Marcial-Quino J, Beristain-Cardoso R. Acclimation of nitrifying biomass and its effect on 2-chlorophenol removal. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2015; 71:277-282. [PMID: 25633952 DOI: 10.2166/wst.2014.508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The metabolic and kinetic behavior of a nitrifying sludge exposed to 2-chlorophenol (2-CP) was evaluated in batch cultures. Two kinds of nitrifying culture were used; one acclimated to 4-methylphenol (4-mp), and the other unacclimated to 4-mp. The unacclimated culture was affected adversely by the 2-CP's presence, since neither nitrification nor 2-CP oxidation was observed. Nonetheless, the acclimated culture showed metabolic capacity to nitrify and mineralize 2-CP. Ammonium removal was 100%, with a nitrifying yield of 0.92 ± 0.04 mg NO(3)(-)-N/mg NH(4)(+)-N consumed. The consumption efficiency for 2-CP was 100% and the halogenated compound was mineralized to CO2. Denaturing gradient gel electrophoresis (DGGE) patterns showed the shift in microbial community structure, indicating that microbial diversity was due to the acclimation process. This is the first evidence where nitrifying culture acclimated to 4-mp completely removed ammonium and 2-CP.
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Affiliation(s)
- J E Pérez-Alfaro
- Departamento de Biotecnología, Universidad Autónoma Metropolitana-Iztapalapa, México, D.F
| | - G González-Blanco
- Departamento de Biotecnología, Universidad Autónoma Metropolitana-Iztapalapa, México, D.F
| | - E Sierra-Palacios
- Academia de Biología, Colegio de Ciencias y Humanidades, Universidad Autónoma de la Ciudad de México, México
| | - J Marcial-Quino
- Cátedras CONACyT, Instituto Nacional de Pediatría, Lab. Bioquímica Genética, Secretaría de Salud, México
| | - R Beristain-Cardoso
- Departamento de Recursos de la Tierra, Universidad Autónoma Metropolitana-Lerma, Edo, México E-mail:
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18
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Martínez-Gutiérrez E, Texier AC, de María Cuervo-López F, Gómez J. Consumption of 2-chlorophenol using anaerobic sludge: physiological and kinetic analysis. Appl Biochem Biotechnol 2014; 174:2171-80. [PMID: 25172056 DOI: 10.1007/s12010-014-1166-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/15/2014] [Indexed: 11/30/2022]
Abstract
Chlorophenols are toxic and recalcitrant compounds produced by many industrial. Different strategies have been used to improve their biological consumption, but there is insufficient information to understand how the process is carried out. The objective of this study was to evaluate in batch tests the effect of the addition of phenol, acetate, or glucose as electron donors at different concentrations on the efficiencies, yields, and specific rates of 2-chlorophenol (2-CP) consumption. The addition of phenol (177.6 mg C/L), acetate (127.6 mg C/L), or glucose (77.6 mg C/L) increased the 2-CP consumption efficiency up to 54.6, 98.6, and 97.8 %, respectively. With respect to the control assay without electron donor, the specific rate of 2-CP consumption was up to 2.5 times higher with phenol (177.6 mg C/L), 8.4 times higher with acetate (127.6 mg C/L), and 3 times higher with glucose (127.6 mg C/L). The results showed that the type and concentration of electron donor determine the physiological behavior of the anaerobic sludge, modifying efficiency, yield, and specific rate values of the 2-CP consumption process. The addition of readily oxidable cosubstrates seems to be a good alternative and might be used for the biological treatment of industrial wastewater polluted with chlorinated phenols.
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Affiliation(s)
- Emir Martínez-Gutiérrez
- Departamento de Biotecnología, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, 09340, Iztapalapa, D.F., Mexico
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19
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Fukushima T, Whang LM, Lee YC, Putri DW, Chen PC, Wu YJ. Transcriptional responses of bacterial amoA gene to dimethyl sulfide inhibition in complex microbial communities. BIORESOURCE TECHNOLOGY 2014; 165:137-144. [PMID: 24666625 DOI: 10.1016/j.biortech.2014.03.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Revised: 02/26/2014] [Accepted: 03/01/2014] [Indexed: 06/03/2023]
Abstract
This study presented an approach by combining the real-time reverse transcription polymerase chain reaction with the terminal restriction fragment length polymorphism (T-RFLP) to investigate transcriptional responses of ammonia-oxidizing bacteria (AOB) to dimethyl sulfide (DMS) inhibition. Batch experiments with added ammonium and DMS were conducted using three activated sludges and Nitrosomonas europaea, and the transcriptional responses of the amo subunit A (amoA) mRNA were evaluated. It was found that DMS inhibited ammonium oxidation and amoA mRNA expression in all batch experiments but the inhibition degree observed was different for different sludges examined. It is likely that the different inhibitory effects of DMS on ammonium oxidation and amoA mRNA expression stemmed from different dominant AOB populations in the sludges. The T-RFLP results for amoA mRNA suggested that inhibition of ammonium oxidation by DMS to Nm. europaea-like AOB with T-RF 219/270 is relatively minor compared to other AOB populations in the examined sludges, such as Nm. europaea-like AOB with T-RF 491/491.
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Affiliation(s)
- Toshikazu Fukushima
- Department of Environmental Engineering, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan
| | - Liang-Ming Whang
- Department of Environmental Engineering, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan; Sustainable Environment Research Laboratory (SERL), National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan; Research Center for Energy Technology and Strategy (RCETS), National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan.
| | - Ya-Ching Lee
- Department of Environmental Engineering, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan
| | - Dyah Wulandari Putri
- Department of Environmental Engineering, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan
| | - Po-Chun Chen
- Department of Environmental Engineering, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan
| | - Yi-Ju Wu
- Department of Environmental Engineering, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan; Sustainable Environment Research Laboratory (SERL), National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan
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20
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Sathyamoorthy S, Chandran K, Ramsburg CA. Biodegradation and cometabolic modeling of selected beta blockers during ammonia oxidation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:12835-12843. [PMID: 24112027 DOI: 10.1021/es402878e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Accurate prediction of pharmaceutical concentrations in wastewater effluents requires that the specific biochemical processes responsible for pharmaceutical biodegradation be elucidated and integrated within any modeling framework. The fate of three selected beta blockers-atenolol, metoprolol, and sotalol-was examined during nitrification using batch experiments to develop and evaluate a new cometabolic process-based (CPB) model. CPB model parameters describe biotransformation during and after ammonia oxidation for specific biomass populations and are designed to be integrated within the Activated Sludge Models framework. Metoprolol and sotalol were not biodegraded by the nitrification enrichment culture employed herein. Biodegradation of atenolol was observed and linked to the activity of ammonia-oxidizing bacteria (AOB) and heterotrophs but not nitrite-oxidizing bacteria. Results suggest that the role of AOB in atenolol degradation may be disproportionately more significant than is otherwise suggested by their lower relative abundance in typical biological treatment processes. Atenolol was observed to competitively inhibit AOB growth in our experiments, though model simulations suggest inhibition is most relevant at atenolol concentrations greater than approximately 200 ng·L(-1). CPB model parameters were found to be relatively insensitive to biokinetic parameter selection suggesting the model approach may hold utility for describing pharmaceutical biodegradation during biological wastewater treatment.
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Affiliation(s)
- Sandeep Sathyamoorthy
- Tufts University , Department of Civil and Environmental Engineering, 200 College Avenue Room 113 Anderson Hall, Medford, Massachusetts 02155, United States
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21
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Lauchnor EG, Semprini L. Inhibition of phenol on the rates of ammonia oxidation by Nitrosomonas europaea grown under batch, continuous fed, and biofilm conditions. WATER RESEARCH 2013; 47:4692-4700. [PMID: 23770483 DOI: 10.1016/j.watres.2013.04.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 03/20/2013] [Accepted: 04/27/2013] [Indexed: 06/02/2023]
Abstract
Ammonia oxidation by Nitrosomonas europaea, an ammonia oxidizing bacterium prevalent in wastewater treatment, is inhibited in the presence of phenol, due to interaction of the phenol with the ammonia monooxygenase enzyme. Suspended cells of N. europaea were cultured in batch reactors and continuous flow reactors at dilution rates of 0.01-0.2 d(-1). The rate of ammonia oxidation in the continuous cultures correlated to the dilution rate in the reactor. The batch and continuous cultures were exposed to 20 μM phenol and ammonia oxidation activity was measured by specific oxygen uptake rates (SOURs). Inhibition of NH3 oxidation by 20 μM phenol ranged from a 77% reduction of SOUR observed with suspended cells harvested during exponential growth, to 26% in biofilms. The extent of inhibition was correlated with ammonia oxidation rates in both suspended and biofilm cells, with greater percent inhibition observed with higher initial rates of NH3 oxidation. In biofilm grown cells, an increase in activity and phenol inhibition were both observed upon dispersing the biofilm cells into fresh, liquid medium. Under higher oxygen tension, an increase in the NO2(-) production of the biofilms was observed and biofilms were more susceptible to phenol inhibition. Dissolved oxygen microsensor measurements showed oxygen limited conditions existed in the biofilms. The ammonia oxidation rate was much lower in biofilms, which were less inhibited during phenol exposure. The results clearly indicate in both suspended and attached cells of N. europaea that a higher extent of phenol inhibition is positively correlated with a higher rate of NH3 oxidation (enzyme turnover).
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Affiliation(s)
- Ellen G Lauchnor
- Center for Biofilm Engineering, Montana State University, 366 EPS, PO Box 173980, Bozeman, MT 59717, USA.
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22
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Hernández SM, Sun W, Sierra-Alvarez R, Field JA. Toluene–nitrite inhibition synergy of anaerobic ammonium oxidizing (anammox) activity. Process Biochem 2013. [DOI: 10.1016/j.procbio.2013.04.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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23
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Radniecki TS, Schneider MC, Semprini L. The influence of Corexit 9500A and weathering on Alaska North Slope crude oil toxicity to the ammonia oxidizing bacterium, Nitrosomonas europaea. MARINE POLLUTION BULLETIN 2013; 68:64-70. [PMID: 23385120 DOI: 10.1016/j.marpolbul.2012.12.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 11/30/2012] [Accepted: 12/03/2012] [Indexed: 06/01/2023]
Abstract
The toxicity of the water associated fraction (WAF) of Alaska North Slope Crude oil (ANSC), Corexit 9500A and the dispersant enhanced WAF (DEWAF) of ANSC:Corexit 9500A mixtures were examined on the model ammonia oxidizing bacterium, Nitrosomonas europaea. Corexit 9500A was not toxic at environmentally relevant concentrations. Corexit 9500A greatly increased the toxicity of ANSC by increasing the chemical oxygen demand (COD) of the DEWAF. However, a majority of the DEWAF compounds were not toxic to N. europaea. Weathered WAF and DEWAF were not toxic to N. europaea even though their COD did not change compared to non-weathered controls, suggesting that toxicity was due to a small volatile fraction of the ANSC. The over-expression of the NE1545 gene, a marker for aromatic hydrocarbon exposure, in N. europaea cells exposed to WAF and DEWAF suggests that aromatic hydrocarbons are bioavailable to the cells and may play a role in the observed toxicity.
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Affiliation(s)
- Tyler S Radniecki
- Department of Civil, Construction and Environmental Engineering, 5500 Campanile Drive, San Diego State University, San Diego, CA 92182-1324, USA.
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24
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Zhang L, Zhang C, Cheng Z, Yao Y, Chen J. Biodegradation of benzene, toluene, ethylbenzene, and o-xylene by the bacterium Mycobacterium cosmeticum byf-4. CHEMOSPHERE 2013; 90:1340-1347. [PMID: 22960059 DOI: 10.1016/j.chemosphere.2012.06.043] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 06/27/2012] [Accepted: 06/27/2012] [Indexed: 06/01/2023]
Abstract
A new strain Mycobacterium cosmeticum byf-4 able to simultaneously degrade benzene, toluene, ethylbenzene, and o-xylene (BTE(o-)X) compounds has been isolated and identified previously in our laboratory. We further report here the extent of degradation of every BTE(o-)X component, and unravel the initial mechanism involved in BTE(o-)X degradation. This organism efficiently degrades all the BTE(o-)X components when these compounds are added either individually or as a composite mixture, and has a preference for toluene followed by benzene, ethylbenzene and then o-xylene. The significantly high carbon recovery indicated that the predominant fate for BTE(o-)X compounds was mineralization and incorporation into cell materials. The presence of BTE compounds in binary or ternary mixtures consistently had a negative effect on o-xylene degradation. The initial steps involved in the degradation of BTE(o-)X were investigated by isolation of metabolites and assay of reverse transcription RT-PCR. Isolation of metabolites suggested that the BTE(o-)X compounds were initially converted by a dioxygenase to their respective catechols. The gene sequence of the PCR amplicons revealed that this isolate contained a 454-bp toluene dioxygenase (TOD) fragment. The BTE(o-)X-specific induction of the genes encoding TOD was confirmed by RT-PCR analysis. These results indicated that TOD was possibly responsible for the initial steps of BTE(o-)X catabolism in M. cosmeticum byf-4.
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Affiliation(s)
- Lili Zhang
- School of Biological and Environmental Engineering, Zhejiang University of Technology, Zhaohui, Hangzhou 310032, China
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25
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Insights into glycogen metabolism in chemolithoautotrophic bacteria from distinctive kinetic and regulatory properties of ADP-glucose pyrophosphorylase from Nitrosomonas europaea. J Bacteriol 2012; 194:6056-65. [PMID: 22961847 DOI: 10.1128/jb.00810-12] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nitrosomonas europaea is a chemolithoautotroph that obtains energy by oxidizing ammonia in the presence of oxygen and fixes CO(2) via the Benson-Calvin cycle. Despite its environmental and evolutionary importance, very little is known about the regulation and metabolism of glycogen, a source of carbon and energy storage. Here, we cloned and heterologously expressed the genes coding for two major putative enzymes of the glycogen synthetic pathway in N. europaea, ADP-glucose pyrophosphorylase and glycogen synthase. In other bacteria, ADP-glucose pyrophosphorylase catalyzes the regulatory step of the synthetic pathway and glycogen synthase elongates the polymer. In starch synthesis in plants, homologous enzymes play similar roles. We purified to homogeneity the recombinant ADP-glucose pyrophosphorylase from N. europaea and characterized its kinetic, regulatory, and oligomeric properties. The enzyme was allosterically activated by pyruvate, oxaloacetate, and phosphoenolpyruvate and inhibited by AMP. It had a broad thermal and pH stability and used different divalent metal ions as cofactors. Depending on the cofactor, the enzyme was able to accept different nucleotides and sugar phosphates as alternative substrates. However, characterization of the recombinant glycogen synthase showed that only ADP-Glc elongates the polysaccharide, indicating that ATP and glucose-1-phosphate are the physiological substrates of the ADP-glucose pyrophosphorylase. The distinctive properties with respect to selectivity for substrates and activators of the ADP-glucose pyrophosphorylase were in good agreement with the metabolic routes operating in N. europaea, indicating an evolutionary adaptation. These unique properties place the enzyme in a category of its own within the family, highlighting the unique regulation in these organisms.
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26
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Arnaout CL, Gunsch CK. Impacts of silver nanoparticle coating on the nitrification potential of Nitrosomonas europaea. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:5387-5395. [PMID: 22533675 DOI: 10.1021/es204540z] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Silver nanoparticles (AgNPs) are increasingly used as bacteriostatic agents to prevent microbial growth. AgNPs are manufactured with a variety of coatings, and their potential impacts on wastewater treatment in general are poorly understood. In the present study, Nitrosomonas europaea, a model ammonia oxidizing bacterium, was exposed to AgNPs with citrate, gum arabic (GA), and polyvinylpyrrolidone (PVP). GA and citrate AgNPs inhibited nitrification most strongly (67.9 ± 3.6% and 91.4 ± 0.2%, respectively at 2 ppm). Our data indicate that Ag(+) dissolution and colloid stability of AgNPs were the main factors in AgNP toxicity. In general, low amounts of dissolved Ag initially caused a post-transcriptional interruption of membrane-bound nitrifying enzyme function, reducing nitrification by 10% or more. A further increase in dissolved Ag resulted in heavy metal stress response (e.g., merA up-regulation) and ultimately led to membrane disruption. The highest effect on membrane disruption was observed for citrate AgNPs (64 ± 11% membranes compromised at 2 ppm), which had high colloidal stability. This study demonstrates that coating plays a very important role in determining Ag dissolution and ultimately toxicity to nitrifiers. More research is needed to characterize these parameters in complex growth media such as wastewater.
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Affiliation(s)
- Christina L Arnaout
- Department of Civil and Environmental Engineering, Duke University, Box 90287, Durham, North Carolina 27708, United States
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27
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Guo Z, Cheng Zhu Y, Huang F, Luttrell R, Leonard R. Microarray analysis of global gene regulation in the Cry1Ab-resistant and Cry1Ab-susceptible strains of Diatraea saccharalis. PEST MANAGEMENT SCIENCE 2012; 68:718-730. [PMID: 22228544 DOI: 10.1002/ps.2318] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2011] [Revised: 08/17/2011] [Accepted: 09/13/2011] [Indexed: 05/31/2023]
Abstract
BACKGROUND Extensive adoption of transgenic Bt corn in recent years for stalk borer control has increased risk of resistance evolution in the target pest populations. A Bt-resistant strain of the sugarcane borer, Diatraea saccharalis, was approximately 100-fold more tolerant to Cry1Ab toxin than the susceptible counterpart. To gain a better understanding of the molecular mechanisms of Bt resistance, the Cry1Ab-susceptible (Cry1Ab-SS) and Cry1Ab-resistant (Cry1Ab-RR) strains of D. saccharalis were subjected to a microarray analysis. RESULTS Results showed that the expression levels of many genes were significantly different between the Cry1Ab-RR and Cry1Ab-SS strains. Microarray analysis of 7145 cDNAs revealed 384 differentially expressed genes. A total of 273 genes were significantly upregulated 2-51.6-fold, and 111 genes were significantly downregulated 2-22.6-fold in the Cry1Ab-RR strain. The upregulation of three potential resistance-related genes, coding for a glutathione S-transferase (GST), a chymotrypsin-like protease (CHY) and a lipase (LP), was confirmed using real-time PCR, indicating a reproducibility of the microarray data. Ontology analysis revealed that more than twice the number of metabolic-related genes were upregulated compared with downregulated genes with the same biological function. Up to 35.2% of the upregulated genes in the resistant strain were associated with catalytic activity, while only 9.5% of the downregulated genes were related to the same catalytic molecular function. CONCLUSION The large portion of metabolic- or catalytic-related genes with significant upregulations indicated a potential large increase in metabolic or catalytic activities in the Cry1Ab-RR strain. This cDNA microarray gene expression data could be used to characterize and identify new genes that may be associated with Bt resistance in D. saccharalis.
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Radniecki TS, Stankus DP, Neigh A, Nason JA, Semprini L. Influence of liberated silver from silver nanoparticles on nitrification inhibition of Nitrosomonas europaea. CHEMOSPHERE 2011; 85:43-49. [PMID: 21757219 DOI: 10.1016/j.chemosphere.2011.06.039] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 05/24/2011] [Accepted: 06/05/2011] [Indexed: 05/29/2023]
Abstract
The ecotoxicity of silver nanoparticles (Ag-NPs) to wastewater biota, including ammonia oxidizing bacteria (AOB), is gaining increasing interest as the number of products containing Ag-NPs continues to rise exponentially and they are expected to accumulate in wastewater treatment plants. This research demonstrated that the addition order of Ag-NP and the media constituents had a profound influence on the stability of the Ag-NP suspension and the corresponding repeatability of results and sensitivity of Nitrosomonas europaea. N. europaea, a model AOB, was found to be extremely sensitive to ionic silver (Ag(+)) and two sizes of Ag-NPs (20 and 80 nm). Ag(+) exposures resulted in the highest level of toxicity with smaller Ag-NPs (20 nm) being more toxic than larger Ag-NPs (80 nm). The increased sensitivity of N. europaea to smaller Ag-NPs was caused by their higher rates of dissolved silver (dAg) release, via dissolution, due to a greater surface area to volume ratio. dAg was shown to be responsible for the vast majority of the observed Ag-NP toxicity, as determined by abiotic Ag-NP dissolution tests. For the sizes of Ag-NP studied (20 and 80 nm), there appears to be a negligible nanoparticle-specific toxicity. This was further supported by similarities in inhibition mechanisms between Ag(+) and Ag-NP, with both causing decreases in AMO activity and destabilization of the outer-membrane of N. europaea. Finally, equal concentrations of total silver were found to be tightly associated to both Ag(+) and Ag-NP-exposed cells despite Ag-NP concentrations being five times greater, by mass, than Ag(+) concentrations.
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Affiliation(s)
- Tyler S Radniecki
- School of Chemical, Biological and Environmental Engineering, 102 Gleeson Hall, Oregon State University, Corvallis, OR 97331, USA.
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Wang S, Gunsch CK. Effects of selected pharmaceutically active compounds on the ammonia oxidizing bacterium Nitrosomonas europaea. CHEMOSPHERE 2011; 82:565-72. [PMID: 20980043 DOI: 10.1016/j.chemosphere.2010.10.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 09/30/2010] [Accepted: 10/03/2010] [Indexed: 05/25/2023]
Abstract
Pharmaceutically active compounds (PhACs) are commonly found in wastewater influent. However, little research has focused on determining their impact on fundamental processes in wastewater treatment such as nitrogen removal. In this study, focus was placed on 4 commonly occurring PhACs (ketoprofen, naproxen, carbamazepine and gemfibrozil). Their effect was ascertained in the ammonia oxidizing bacterium (AOB), Nitrosomonas europaea in terms of membrane integrity and nitrite production. These PhACs were shown to inhibit nitrite production at concentrations of 1 and 10 μM while no effect was observed at 0.1 μM. The maximum observed nitrification inhibition was 25%, 29%, 22% and 26% for ketoprofen, naproxen, carbamazepine and gemfibrozil, respectively. A decrease in the live/dead ratio ranging from 10% to 16% suggests that these PhACs affect membrane integrity in N.europaea. The difference in nitrite production between PhACs treated cells and non PhAC treated controls was still significant following washing suggesting that inhibition is irreversible. Finally, nitrite production when adjusted to the live fraction of cells was also found to decrease suggesting that PhACs inhibited the activity of surviving cells. These results suggest that the presence of PhACs may affect AOB activity and may impact nitrogen removal, a key function in wastewater treatment. Follow up studies with additional AOB and in mixed culture are needed to further confirm these results.
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Affiliation(s)
- Shuyi Wang
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
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Investigating Nitrosomonas europaea Stress Biomarkers in Batch, Continuous Culture, and Biofilm Reactors. Methods Enzymol 2011; 496:217-46. [DOI: 10.1016/b978-0-12-386489-5.00009-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Radniecki TS, Gilroy CA, Semprini L. Linking NE1545 gene expression with cell volume changes in Nitrosomonas europaea cells exposed to aromatic hydrocarbons. CHEMOSPHERE 2011; 82:514-520. [PMID: 21106218 DOI: 10.1016/j.chemosphere.2010.10.083] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 10/25/2010] [Accepted: 10/26/2010] [Indexed: 05/30/2023]
Abstract
Nitrosomonas europaea, a model ammonia oxidizing bacterium, was exposed to a wide variety of aromatic hydrocarbons in 3 h batch assays. The expression of NE1545, a phenol sentinel gene involved in fatty acid metabolism, was monitored via quantitative real-time polymerase chain reaction (qRT-PCR) and a Coulter Counter technique was used to monitor changes in cell volume. Decreases in cell volume and NE1545 gene expression correlated strongly with exposure to aromatic hydrocarbons that possessed a single polar group substitution (e.g. phenol and aniline). Aromatic hydrocarbons that contain no polar group substitutions (e.g. toluene) or multiple polar group substitutions (e.g. p-hydroquinone) caused negligible changes in NE1545 expression and cell volume. The oxidation of aromatic hydrocarbons by N. europaea from configurations without a single polar group to one with two polar groups (e.g. p-cresol oxidized to 4-hydroxybenzyl alcohol) and from configurations with no polar groups to one with a single polar group (e.g. ethylbenzene oxidized to 4-ethylphenol) greatly influenced NE1545 gene expression and observed changes in cell volume. Nitrification inhibition in N. europaea by the aromatic hydrocarbons was found to be completely reversible; however, the decreases in cell volume were not reversible suggesting a physical change in cell membrane composition. Ammonia monooxygenase blocking studies showed that the chemical exposure that was responsible for the cell volume decrease and up-regulation in gene expression and not the observed inhibition. N. europaea is the first bacterium shown to experience significant changes in cell volume when exposed to μM concentrations of aromatic hydrocarbons, three orders of magnitude lower than previous studies with other bacteria.
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Lauchnor EG, Radniecki TS, Semprini L. Inhibition and gene expression of Nitrosomonas europaea biofilms exposed to phenol and toluene. Biotechnol Bioeng 2010; 108:750-7. [PMID: 21404249 DOI: 10.1002/bit.22999] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 10/23/2010] [Accepted: 10/26/2010] [Indexed: 11/08/2022]
Abstract
Pure culture biofilms of the ammonia-oxidizing bacterium Nitrosomonas europaea were grown in a Drip Flow Biofilm Reactor and exposed to the aromatic hydrocarbons phenol and toluene. Ammonia oxidation rates, as measured by nitrite production in the biofilms, were inhibited 50% when exposed to 56 µM phenol or 100 µM toluene, while 50% inhibition of suspended cells occurred at 8 µM phenol or 20 µM toluene. Biofilm-grown cells dispersed into liquid medium and immediately exposed to phenol or toluene experienced similar inhibition levels as batch grown cells, indicating that mass transfer may be a factor in N. europaea biofilm resistance. Whole genome microarray analysis of gene expression was used to detect genes up-regulated in biofilms during toluene and phenol exposure. Two genes, a putative pirin protein (NE1545) and a putative inner membrane protein (NE1546) were up-regulated during phenol exposure, but no genes were up-regulated during toluene exposure. Using qRT-PCR, up-regulation of NE1545 was detected in biofilms and suspended cells exposed to a range of phenol concentrations and levels of inhibition. In the biofilms, NE1545 expression was up-regulated an average of 13-fold over the range of phenol concentrations tested, and was essentially independent of phenol concentration. However, the expression of NE1545 in suspended cells increased from 20-fold at 7 µM phenol up to 80-fold at 30 µM phenol. This study demonstrates that biofilms of N. europaea are more resistant than suspended cells to inhibition of ammonia oxidation by phenol and toluene, even though the global transcriptional responses to the inhibitors do not differ in N. europaea between the suspended and attached growth states.
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Affiliation(s)
- Ellen G Lauchnor
- School of Chemical, Biological and Environmental Engineering, 102 Gleeson Hall, Oregon State University, Corvallis, Oregon 97331, USA
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Figuerola ELM, Erijman L. Diversity of nitrifying bacteria in a full-scale petroleum refinery wastewater treatment plant experiencing unstable nitrification. JOURNAL OF HAZARDOUS MATERIALS 2010; 181:281-288. [PMID: 20570044 DOI: 10.1016/j.jhazmat.2010.05.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2010] [Revised: 03/27/2010] [Accepted: 05/03/2010] [Indexed: 05/29/2023]
Abstract
We have investigated bacterial populations relevant to nitrification in a full-scale activated sludge plant receiving wastewater from a petroleum refinery showing unstable nitrification. Inhibition of ammonia oxidation was related to phenol concentration according to a model of non-competitive inhibition. While the number of ammonia-oxidizing bacteria (AOB) did not correlate with nitrification performance, the total number of nitrite-oxidizing bacteria (NOB) dropped considerably during periods of nitrite accumulation or no nitrification. Diversity of nitrifiers in the sludge of the full-scale facility was examined at a time of full nitrification with the construction of clone libraries of ammonia monooxygenase (amoA) gene and of the 16S rRNA gene of NOB. Nucleotide sequences of amoA gene belonged to one dominant population, associated with Nitrosomonas europaea, and to a minor population related to the Nitrosomonas nitrosa lineage. The majority of sequences retrieved in the NOB-like clone library also clustered within a single operational taxonomic unit. The high dominance of Nitrobacter over Nitrospira and the low diversity of nitrifying bacteria observed in this wastewater treatment plant might account for the increased risk of failure in the presence of disturbances.
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Affiliation(s)
- Eva L M Figuerola
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Buenos Aires, Argentina
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Gvakharia BO, Tjaden B, Vajrala N, Sayavedra-Soto LA, Arp DJ. Computational prediction and transcriptional analysis of sRNAs in Nitrosomonas europaea. FEMS Microbiol Lett 2010; 312:46-54. [PMID: 20840601 DOI: 10.1111/j.1574-6968.2010.02095.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Bacterial small noncoding RNAs (sRNAs) have been discovered in many genetically well-studied microorganisms and have been shown to regulate critical cellular processes at the post-transcriptional level. In this study, we used comparative genomics and microarray data to analyze the genome of the ammonia-oxidizing bacterium Nitrosomonas europaea for the presence and expression of sRNAs. Fifteen genes encoding putative sRNAs (psRNAs) were identified. Most of these genes showed altered expression in a variety of experimental conditions. The transcripts of two psRNAs were further characterized by mapping their 5'- and 3'-ends and by real-time PCR. The results of these analyses suggested that one of them, psRNA11, is involved in iron homeostasis in N. europaea.
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Affiliation(s)
- Barbara O Gvakharia
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
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Bhaganna P, Volkers RJM, Bell ANW, Kluge K, Timson DJ, McGrath JW, Ruijssenaars HJ, Hallsworth JE. Hydrophobic substances induce water stress in microbial cells. Microb Biotechnol 2010; 3:701-16. [PMID: 21255365 PMCID: PMC3815343 DOI: 10.1111/j.1751-7915.2010.00203.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Ubiquitous noxious hydrophobic substances, such as hydrocarbons, pesticides and diverse industrial chemicals, stress biological systems and thereby affect their ability to mediate biosphere functions like element and energy cycling vital to biosphere health. Such chemically diverse compounds may have distinct toxic activities for cellular systems; they may also share a common mechanism of stress induction mediated by their hydrophobicity. We hypothesized that the stressful effects of, and cellular adaptations to, hydrophobic stressors operate at the level of water : macromolecule interactions. Here, we present evidence that: (i) hydrocarbons reduce structural interactions within and between cellular macromolecules, (ii) organic compatible solutes – metabolites that protect against osmotic and chaotrope‐induced stresses – ameliorate this effect, (iii) toxic hydrophobic substances induce a potent form of water stress in macromolecular and cellular systems, and (iv) the stress mechanism of, and cellular responses to, hydrophobic substances are remarkably similar to those associated with chaotrope‐induced water stress. These findings suggest that it may be possible to devise new interventions for microbial processes in both natural environments and industrial reactors to expand microbial tolerance of hydrophobic substances, and hence the biotic windows for such processes.
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Affiliation(s)
- Prashanth Bhaganna
- Department of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK
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Nitrification and degradation of halogenated hydrocarbons--a tenuous balance for ammonia-oxidizing bacteria. Appl Microbiol Biotechnol 2010; 86:435-44. [PMID: 20146060 DOI: 10.1007/s00253-010-2454-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Revised: 01/14/2010] [Accepted: 01/14/2010] [Indexed: 10/19/2022]
Abstract
The process of nitrification has the potential for the in situ bioremediation of halogenated compounds provided a number of challenges can be overcome. In nitrification, the microbial process where ammonia is oxidized to nitrate, ammonia-oxidizing bacteria (AOB) are key players and are capable of carrying out the biodegradation of recalcitrant halogenated compounds. Through industrial uses, halogenated compounds often find their way into wastewater, contaminating the environment and bodies of water that supply drinking water. In the reclamation of wastewater, halogenated compounds can be degraded by AOB but can also be detrimental to the process of nitrification. This minireview considers the ability of AOB to carry out cometabolism of halogenated compounds and the consequent inhibition of nitrification. Possible cometabolism monitoring methods that were derived from current information about AOB genomes are also discussed. AOB expression microarrays have detected mRNA of genes that are expressed at higher levels during stress and are deemed "sentinel" genes. Promoters of selected "sentinel" genes have been cloned and used to drive the expression of gene-reporter constructs. The latter are being tested as early warning biosensors of cometabolism-induced damage in Nitrosomonas europaea with promising results. These and other biosensors may help to preserve the tenuous balance that exists when nitrification occurs in waste streams containing alternative AOB substrates such as halogenated hydrocarbons.
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Gvakharia BO, Bottomley PJ, Arp DJ, Sayavedra-Soto LA. Construction of recombinant Nitrosomonas europaea expressing green fluorescent protein in response to co-oxidation of chloroform. Appl Microbiol Biotechnol 2009; 82:1179-85. [PMID: 19247648 DOI: 10.1007/s00253-009-1914-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 02/05/2009] [Accepted: 02/08/2009] [Indexed: 11/29/2022]
Abstract
Transcriptional fusions with gfp driven by the promoter region of mbla (NE2571) in pPRO/mbla4 and clpB (NE2402) in pPRO/clpb7 were used to transform the ammonia-oxidizing bacterium Nitrosomonas europaea (ATCC 19718). The two genes were chosen because their transcript levels were found at much higher levels in N. europaea in response to oxidation of chloroform and chloromethane. In N. europaea transformed with pPRO/mbla4, green fluorescent protein (GFP)-dependent fluorescence increased from 3- to 18-fold above control levels in response to increasing chloroform concentrations (7 to 28 microM), and from 8- to 10-fold in response to increasing hydrogen peroxide concentrations (2.5-7.5 mM). The GFP-dependent fluorescence of N. europaea transformed with pPRO/clpb7 also showed an increase of 6- to 10-fold in response to chloroform (28-100 microM) but did not respond to H(2)O(2). Our data provide proof of concept that biosensors can be fabricated in ammonia-oxidizing bacteria using "sentinel" genes that up-regulate in response to stress caused either by co-oxidation of chlorinated solvents or by the presence of H(2)O(2). The fabricated biosensors had a consistent concentration-dependent response to chloroform; however, these did not respond to other chlorinated compounds that cause similar cellular stress.
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Affiliation(s)
- Barbara O Gvakharia
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
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