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Zhu X, Wang K, Liu C, Wu Y, Wu E, Lv J, Xiao X, Zhu X, Chu C, Chen B. Natural Disinfection-like Process Unveiled in Soil Microenvironments by Enzyme-Catalyzed Chlorination. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:3838-3848. [PMID: 38351523 DOI: 10.1021/acs.est.3c07924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Substantial natural chlorination processes are a growing concern in diverse terrestrial ecosystems, occurring through abiotic redox reactions or biological enzymatic reactions. Among these, exoenzymatically mediated chlorination is suggested to be an important pathway for producing organochlorines and converting chloride ions (Cl-) to reactive chlorine species (RCS) in the presence of reactive oxygen species like hydrogen peroxide (H2O2). However, the role of natural enzymatic chlorination in antibacterial activity occurring in soil microenvironments remains unexplored. Here, we conceptualized that heme-containing chloroperoxidase (CPO)-catalyzed chlorination functions as a naturally occurring disinfection process in soils. Combining antimicrobial experiments and microfluidic chip-based fluorescence imaging, we showed that the enzymatic chlorination process exhibited significantly enhanced antibacterial activity against Escherichia coli and Bacillus subtilis compared to H2O2. This enhancement was primarily attributed to in situ-formed RCS. Based on semiquantitative imaging of RCS distribution using a fluorescence probe, the effective distance of this antibacterial effect was estimated to be approximately 2 mm. Ultrahigh-resolution mass spectrometry analysis showed over 97% similarity between chlorine-containing formulas from CPO-catalyzed chlorination and abiotic chlorination (by sodium hypochlorite) of model dissolved organic matter, indicating a natural source of disinfection byproduct analogues. Our findings unveil a novel natural disinfection process in soils mediated by indigenous enzymes, which effectively links chlorine-carbon interactions and reactive species dynamics.
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Affiliation(s)
- Xiangyu Zhu
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang 310058, China
| | - Kun Wang
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
- ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, China
| | - Congcong Liu
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang 310058, China
| | - Yajing Wu
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang 310058, China
| | - Enhui Wu
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang 310058, China
| | - Jitao Lv
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Xiao
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang 310058, China
| | - Xiaoying Zhu
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang 310058, China
| | - Chiheng Chu
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang 310058, China
| | - Baoliang Chen
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang 310058, China
- Innovation Center of Yangtze River Delta, Zhejiang University, Zhejiang 311400, China
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Gribble GW. Naturally Occurring Organohalogen Compounds-A Comprehensive Review. PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS 2023; 121:1-546. [PMID: 37488466 DOI: 10.1007/978-3-031-26629-4_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
The present volume is the third in a trilogy that documents naturally occurring organohalogen compounds, bringing the total number-from fewer than 25 in 1968-to approximately 8000 compounds to date. Nearly all of these natural products contain chlorine or bromine, with a few containing iodine and, fewer still, fluorine. Produced by ubiquitous marine (algae, sponges, corals, bryozoa, nudibranchs, fungi, bacteria) and terrestrial organisms (plants, fungi, bacteria, insects, higher animals) and universal abiotic processes (volcanos, forest fires, geothermal events), organohalogens pervade the global ecosystem. Newly identified extraterrestrial sources are also documented. In addition to chemical structures, biological activity, biohalogenation, biodegradation, natural function, and future outlook are presented.
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Affiliation(s)
- Gordon W Gribble
- Department of Chemistry, Dartmouth College, Hanover, NH, 03755, USA.
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3
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Barnum TP, Coates JD. Chlorine redox chemistry is widespread in microbiology. THE ISME JOURNAL 2023; 17:70-83. [PMID: 36202926 PMCID: PMC9751292 DOI: 10.1038/s41396-022-01317-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 11/07/2022]
Abstract
Chlorine is abundant in cells and biomolecules, yet the biology of chlorine oxidation and reduction is poorly understood. Some bacteria encode the enzyme chlorite dismutase (Cld), which detoxifies chlorite (ClO2-) by converting it to chloride (Cl-) and molecular oxygen (O2). Cld is highly specific for chlorite and aside from low hydrogen peroxide activity has no known alternative substrate. Here, we reasoned that because chlorite is an intermediate oxidation state of chlorine, Cld can be used as a biomarker for oxidized chlorine species. Cld was abundant in metagenomes from various terrestrial habitats. About 5% of bacterial and archaeal genera contain a microorganism encoding Cld in its genome, and within some genera Cld is highly conserved. Cld has been subjected to extensive horizontal gene transfer. Genes found to have a genetic association with Cld include known genes for responding to reactive chlorine species and uncharacterized genes for transporters, regulatory elements, and putative oxidoreductases that present targets for future research. Cld was repeatedly co-located in genomes with genes for enzymes that can inadvertently reduce perchlorate (ClO4-) or chlorate (ClO3-), indicating that in situ (per)chlorate reduction does not only occur through specialized anaerobic respiratory metabolisms. The presence of Cld in genomes of obligate aerobes without such enzymes suggested that chlorite, like hypochlorous acid (HOCl), might be formed by oxidative processes within natural habitats. In summary, the comparative genomics of Cld has provided an atlas for a deeper understanding of chlorine oxidation and reduction reactions that are an underrecognized feature of biology.
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Affiliation(s)
- Tyler P Barnum
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
| | - John D Coates
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA.
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4
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Svensson T, Redon PO, Thiry Y, Montelius M, Bastviken D. Chlorination of soil organic matter: The role of humus type and land use. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:150478. [PMID: 34582876 DOI: 10.1016/j.scitotenv.2021.150478] [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: 05/21/2021] [Revised: 09/15/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
The levels of natural organic chlorine (Clorg) typically exceed levels of chloride in most soils and is therefore clearly of high importance for continental chlorine cycling. The high spatial variability raises questions on soil organic matter (SOM) chlorination rates among topsoils with different types of organic matter. We measured Clorg formation rates along depth profiles in six French temperate soils with similar Cl deposition using 36Cl tracer experiments. Three forest sites with different humus types and soils from grassland and arable land were studied. The highest specific chlorination rates (fraction of chlorine pool transformed to Clorg per time unit) among the forest soils were found in the humus layers. Comparing the forest sites, specific chlorination was highest in mull-type humus, characterized by high microbial activity and fast degradation of the organic matter. Considering non-humus soil layers, grassland and forest soils had similar specific chlorination rates in the uppermost layer (0-10 cm below humus layer). Below this depth the specific chlorination rate decreased slightly in forests, and drastically in the grassland soil. The agricultural soil exhibited the lowest specific chlorination rates, similar along the depth profile. Across all sites, specific chlorination rates were correlated with soil moisture and in combination with the patterns on organic matter types, the results suggest an extensive Cl cycling where humus types and soil moisture provided best conditions for microbial activity. Clorg accumulation and theoretical residence times were not clearly linked to chlorination rates. This indicates intensive Cl cycling between organic and inorganic forms in forest humus layers, regulated by humic matter reactivity and soil moisture, while long-term Clorg accumulation seems more linked with overall deep soil organic carbon stabilization. Thus, humus types and factors affecting soil carbon storage, including vegetation land use, could be used as indicators of potential Clorg formation and accumulation in soils.
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Affiliation(s)
- Teresia Svensson
- Department of Thematic Studies - Environmental Change, Linköping University, 581 83 Linköping, Sweden.
| | - Paul-Olivier Redon
- Andra, Research and Development Division, 1/7 rue Jean-Monnet, 92298 Chatenay-Malabry Cedex, France
| | - Yves Thiry
- Andra, Research and Development Division, 1/7 rue Jean-Monnet, 92298 Chatenay-Malabry Cedex, France
| | - Malin Montelius
- Swedish Geotechnical Institute (SGI), 581 93 Linköping, Sweden
| | - David Bastviken
- Department of Thematic Studies - Environmental Change, Linköping University, 581 83 Linköping, Sweden
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Long Y, Li H, Jin H, Ni J. Interpretation of high perchlorate generated during electrochemical disinfection in presence of chloride at BDD anodes. CHEMOSPHERE 2021; 284:131418. [PMID: 34323797 DOI: 10.1016/j.chemosphere.2021.131418] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 05/31/2021] [Accepted: 06/30/2021] [Indexed: 06/13/2023]
Abstract
Perchlorate is a disinfection by-product (DBP) of serious health concern. Herein, the long sought mechanism of high perchlorate production during electrochemical disinfection at boron-doped diamond (BDD) anode in the presence of chloride was elucidated. The generated perchlorate at BDD during electrochemical disinfection (in 10 mM NaCl) in 60 min reached 0.125 mM, which was 830 times higher than the EPA standard. In contrast, perchlorate at PbO2 and SnO2 anodes was below the detection limit. Further experiments employing NaClO3 revealed that the conversion ratio from ClO3- to ClO4- in 10 h at BDD (98%) was considerably higher than PbO2 (13%) and SnO2 (12%). Such significant difference among anodes was fully interpreted with a two-step mechanism. The first step is essential to produce ·ClO3 by oxidizing ClO3- at electrodes. Otherwise, the conversion to perchlorate would be impossible even with excessive ·OH, which was verified with the photocatalysis process. The second step is the perchlorate generation with radical reaction between ·ClO3 and ·OH, where the primary role of ·OH was substantiated by scavenging test. Interestingly, the capability of perchlorate production was correlated with free ·OH instead of the total amount of ·OH. Despite the similar abilities of electron transfer between anodes and ClO3-, much higher free ·OH exists at BDD anode than at PbO2 and SnO2 anodes through chronoamperometry experiments and work function characterization, which reasonably provides interpretation of high perchlorate production at BDD anode.
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Affiliation(s)
- Yujiao Long
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China; College of Environmental Sciences and Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, 100871, China
| | - Hongna Li
- Agricultural Clean Watershed Research Group, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Hongmei Jin
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China
| | - Jinren Ni
- College of Environmental Sciences and Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, 100871, China.
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Svensson T, Kylin H, Montelius M, Sandén P, Bastviken D. Chlorine cycling and the fate of Cl in terrestrial environments. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:7691-7709. [PMID: 33400105 PMCID: PMC7854439 DOI: 10.1007/s11356-020-12144-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 12/16/2020] [Indexed: 05/11/2023]
Abstract
Chlorine (Cl) in the terrestrial environment is of interest from multiple perspectives, including the use of chloride as a tracer for water flow and contaminant transport, organochlorine pollutants, Cl cycling, radioactive waste (radioecology; 36Cl is of large concern) and plant science (Cl as essential element for living plants). During the past decades, there has been a rapid development towards improved understanding of the terrestrial Cl cycle. There is a ubiquitous and extensive natural chlorination of organic matter in terrestrial ecosystems where naturally formed chlorinated organic compounds (Clorg) in soil frequently exceed the abundance of chloride. Chloride dominates import and export from terrestrial ecosystems while soil Clorg and biomass Cl can dominate the standing stock Cl. This has important implications for Cl transport, as chloride will enter the Cl pools resulting in prolonged residence times. Clearly, these pools must be considered separately in future monitoring programs addressing Cl cycling. Moreover, there are indications that (1) large amounts of Cl can accumulate in biomass, in some cases representing the main Cl pool; (2) emissions of volatile organic chlorines could be a significant export pathway of Cl and (3) that there is a production of Clorg in tissues of, e.g. plants and animals and that Cl can accumulate as, e.g. chlorinated fatty acids in organisms. Yet, data focusing on ecosystem perspectives and combined spatiotemporal variability regarding various Cl pools are still scarce, and the processes and ecological roles of the extensive biological Cl cycling are still poorly understood.
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Affiliation(s)
- Teresia Svensson
- Department of Thematic Studies - Environmental Change, Linköping University, SE-581 83, Linkoping, Sweden.
| | - Henrik Kylin
- Department of Thematic Studies - Environmental Change, Linköping University, SE-581 83, Linkoping, Sweden
- Research Unit: Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Malin Montelius
- Swedish Geotechnical Institute (SGI), SE-581 93, Linkoping, Sweden
| | - Per Sandén
- Department of Thematic Studies - Environmental Change, Linköping University, SE-581 83, Linkoping, Sweden
| | - David Bastviken
- Department of Thematic Studies - Environmental Change, Linköping University, SE-581 83, Linkoping, Sweden
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Organohalide-Respiring Bacteria at the Heart of Anaerobic Metabolism in Arctic Wet Tundra Soils. Appl Environ Microbiol 2021; 87:AEM.01643-20. [PMID: 33187999 DOI: 10.1128/aem.01643-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 11/10/2020] [Indexed: 11/20/2022] Open
Abstract
Recent work revealed an active biological chlorine cycle in coastal Arctic tundra of northern Alaska. This raised the question of whether chlorine cycling was restricted to coastal areas or if these processes extended to inland tundra. The anaerobic process of organohalide respiration, carried out by specialized bacteria like Dehalococcoides, consumes hydrogen gas and acetate using halogenated organic compounds as terminal electron acceptors, potentially competing with methanogens that produce the greenhouse gas methane. We measured microbial community composition and soil chemistry along an ∼262-km coastal-inland transect to test for the potential of organohalide respiration across the Arctic Coastal Plain and studied the microbial community associated with Dehalococcoides to explore the ecology of this group and its potential to impact C cycling in the Arctic. Concentrations of brominated organic compounds declined sharply with distance from the coast, but the decrease in organic chlorine pools was more subtle. The relative abundances of Dehalococcoides were similar across the transect, except for being lower at the most inland site. Dehalococcoides correlated with other strictly anaerobic genera, plus some facultative ones, that had the genetic potential to provide essential resources (hydrogen, acetate, corrinoids, or organic chlorine). This community included iron reducers, sulfate reducers, syntrophic bacteria, acetogens, and methanogens, some of which might also compete with Dehalococcoides for hydrogen and acetate. Throughout the Arctic Coastal Plain, Dehalococcoides is associated with the dominant anaerobes that control fluxes of hydrogen, acetate, methane, and carbon dioxide. Depending on seasonal electron acceptor availability, organohalide-respiring bacteria could impact carbon cycling in Arctic wet tundra soils.IMPORTANCE Once considered relevant only in contaminated sites, it is now recognized that biological chlorine cycling is widespread in natural environments. However, linkages between chlorine cycling and other ecosystem processes are not well established. Species in the genus Dehalococcoides are highly specialized, using hydrogen, acetate, vitamin B12-like compounds, and organic chlorine produced by the surrounding community. We studied which neighbors might produce these essential resources for Dehalococcoides species. We found that Dehalococcoides species are ubiquitous across the Arctic Coastal Plain and are closely associated with a network of microbes that produce or consume hydrogen or acetate, including the most abundant anaerobic bacteria and methanogenic archaea. We also found organic chlorine and microbes that can produce these compounds throughout the study area. Therefore, Dehalococcoides could control the balance between carbon dioxide and methane (a more potent greenhouse gas) when suitable organic chlorine compounds are available to drive hydrogen and acetate uptake.
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8
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Tanaka T, Thiry Y. Assessing the recycling of chlorine and its long-lived 36Cl isotope in terrestrial ecosystems through dynamic modeling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 700:134482. [PMID: 31689653 DOI: 10.1016/j.scitotenv.2019.134482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/12/2019] [Accepted: 09/14/2019] [Indexed: 06/10/2023]
Abstract
It is unclear to what extent chlorine (Cl) and its long-lived isotope 36Cl are recycled in different terrestrial environments in response to time-variable inputs. A new version of a dynamic compartment model was developed to examine the transformation and transfer processes influencing the partitioning and persistence of both Cl and 36Cl in forest ecosystems. The model's performance was evaluated by comparing simulations and field observations of scenarios of stable Cl atmospheric deposition and of global 36Cl fallout. The model reproduced Cl storage in soil reasonably well, despite wide heterogeneity in environmental conditions and atmospheric deposits. Sensitivity analysis confirmed that the natural production of organochlorine in soil plays a major role in Cl build-up and affects long-term Cl dynamics. The timeframe required for the soil organochlorine pool to reach equilibrium in a steady-state system was several thousands of years. Interestingly, root uptake flux, a predominant pathway of the inorganic cycle, was found to affect both inorganic and organic pools in soil, highlighting the importance of plant-soil interactions in Cl dynamics. Model outputs agreed well with local 36Cl measurements, and demonstrated that 90% of the 36Cl found in soil may have come from bomb-test fallout. The pattern of estimated 36Cl/Cl ratios showed that soil 36Cl was not in equilibrium with 36Cl levels in rain input in the post-bomb period. Complete recovery of a natural isotopic ratio in drainage water will need a time close to the residence time of organic 36Cl in soil: i.e., 800 years. A simple dynamic model concept was found to be suitable to illustrate the plant-soil interactions combining both the inorganic and organic Cl cycles acting over different time scales.
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Affiliation(s)
- Taku Tanaka
- EDF R&D, LNHE, 6 Quai Watier, 78400 Chatou, France.
| | - Yves Thiry
- Andra, Research and Development Division, 1-7 Rue Jean-Monnet, 92298 Châtenay-Malabry cedex, France.
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Wang K, Huang X, Lin K. Multiple catalytic roles of chloroperoxidase in the transformation of phenol: Products and pathways. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 179:96-103. [PMID: 31026755 DOI: 10.1016/j.ecoenv.2019.04.061] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 04/15/2019] [Accepted: 04/19/2019] [Indexed: 06/09/2023]
Abstract
Chloroperoxidase (CPO) is a hybrid of two different families of enzymes, peroxidases and P450s. However, it is poorly understood on CPO's multiple catalytic functions. Herein, phenol was selected as a model substrate to investigate the multiple catalytic roles of CPO. Results showed that phenol was readily transformed into a variety of brominated organic compounds (BOCs) via the CPO-mediated oxidative process. A total of 16 BOCs were identified using gas and liquid chromatography coupled with mass spectrometry. Possible reaction pathways could be attributable to four CPO-mediated processes, including bromination, radical coupling, intramolecular cyclization and debromination. Higher bromide concentrations and lower pH conditions both facilitated the formation of brominated products. While a higher bromination capacity was observed in pH 3.0 solutions, CPO-mediated radical couplings were more favorable at pH 5.0 and 6.0. Although CPO might catalyze chlorination when chloride and bromide coexisted in the solution, BOCs were the dominant products of CPO-mediated phenol oxidation. Results of this study suggest that various catalytic roles of CPO may contribute to the biotic formation of BOCs in the natural environment.
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Affiliation(s)
- Kun Wang
- The Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Center for Marine Environmental Chemistry and Toxicology, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China
| | - Xinwen Huang
- College of Environment, Zhejiang University of Technology, Hangzhou, 310032, China
| | - Kunde Lin
- The Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Center for Marine Environmental Chemistry and Toxicology, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China.
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McLauchlan CC, Murakami HA, Wallace CA, Crans DC. Coordination environment changes of the vanadium in vanadium-dependent haloperoxidase enzymes. J Inorg Biochem 2018; 186:267-279. [PMID: 29990751 DOI: 10.1016/j.jinorgbio.2018.06.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 06/11/2018] [Accepted: 06/14/2018] [Indexed: 11/17/2022]
Abstract
Vanadium-dependent haloperoxidases are a class of enzymes that catalyze oxidation reactions with halides to form halogenated organic products and water. These enzymes include chloroperoxidase and bromoperoxidase, which have very different protein sequences and sizes, but regardless the coordination environment of the active sites is surprisingly constant. In this manuscript, the comparison of the coordination chemistry of V-containing-haloperoxidases of the trigonal bipyramidal geometry was done by data mining. The catalytic cycle imposes changes in the coordination geometry of the vanadium to accommodate the peroxidovanadium(V) intermediate in an environment we describe as a distorted square pyramidal geometry. During the catalytic cycle, this intermediate converts to a trigonal bipyramidal intermediate before losing the halogen and forming a tetrahedral vanadium-protein intermediate. Importantly, the catalysis is facilitated by a proton-relay system supplied by the second sphere coordination environment and the changes in the coordination environment of the vanadium(V) making this process unique among protein catalyzed processes. The analysis of the coordination chemistry shows that the active site is very tightly regulated with only minor changes in the coordination geometry. The coordination geometry in the protein structures deviates from that found for both small molecules crystalized in the absence of protein and the reported functional small molecule model compounds. At this time there are no examples reported of a structurally similar small molecule with the geometry observed for the peroxidovanadium(V) in the active site of the vanadium-containing haloperoxidases.
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Affiliation(s)
- Craig C McLauchlan
- Department of Chemistry, Illinois State University, Campus Box 4160, Normal, IL 61790, USA.
| | - Heide A Murakami
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
| | - Craig A Wallace
- Department of Chemistry, Illinois State University, Campus Box 4160, Normal, IL 61790, USA
| | - Debbie C Crans
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA; Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO 80523, USA.
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11
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Svensson T, Montelius M, Andersson M, Lindberg C, Reyier H, Rietz K, Danielsson Å, Bastviken D. Influence of Multiple Environmental Factors on Organic Matter Chlorination in Podsol Soil. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:14114-14123. [PMID: 29172517 DOI: 10.1021/acs.est.7b03196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Natural chlorination of organic matter is common in soils. The abundance of chlorinated organic compounds frequently exceeds chloride in surface soils, and the ability to chlorinate soil organic matter (SOM) appears widespread among microorganisms. Yet, the environmental control of chlorination is unclear. Laboratory incubations with 36Cl as a Cl tracer were performed to test how combinations of environmental factors, including levels of soil moisture, nitrate, chloride, and labile organic carbon, influenced chlorination of SOM from a boreal forest. Total chlorination was hampered by addition of nitrate or by nitrate in combination with water but enhanced by addition of chloride or most additions including labile organic matter (glucose and maltose). The greatest chlorination was observed after 15 days when nitrate and water were added together with labile organic matter. The effect that labile organic matter strongly stimulated the chlorination rates was confirmed by a second independent experiment showing higher stimulation at increased availability of labile organic matter. Our results highlight cause-effect links between chlorination and the studied environmental variables in podsol soil-with consistent stimulation by labile organic matter that did overrule the negative effects of nitrate.
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Affiliation(s)
- Teresia Svensson
- Department of Thematic Studies, Environmental Change, Linköping University , SE-581 83 Linköping, Sweden
| | - Malin Montelius
- Department of Thematic Studies, Environmental Change, Linköping University , SE-581 83 Linköping, Sweden
| | - Malin Andersson
- Department of Thematic Studies, Environmental Change, Linköping University , SE-581 83 Linköping, Sweden
| | - Cecilia Lindberg
- Department of Thematic Studies, Environmental Change, Linköping University , SE-581 83 Linköping, Sweden
| | - Henrik Reyier
- Department of Thematic Studies, Environmental Change, Linköping University , SE-581 83 Linköping, Sweden
| | - Karolina Rietz
- Department of Thematic Studies, Environmental Change, Linköping University , SE-581 83 Linköping, Sweden
| | - Åsa Danielsson
- Department of Thematic Studies, Environmental Change, Linköping University , SE-581 83 Linköping, Sweden
| | - David Bastviken
- Department of Thematic Studies, Environmental Change, Linköping University , SE-581 83 Linköping, Sweden
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12
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Atashgahi S, Häggblom MM, Smidt H. Organohalide respiration in pristine environments: implications for the natural halogen cycle. Environ Microbiol 2017; 20:934-948. [PMID: 29215190 DOI: 10.1111/1462-2920.14016] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 11/29/2017] [Accepted: 12/01/2017] [Indexed: 11/29/2022]
Abstract
Halogenated organic compounds, also termed organohalogens, were initially considered to be of almost exclusively anthropogenic origin. However, over 5000 naturally synthesized organohalogens are known today. This has also fuelled the hypothesis that the natural and ancient origin of organohalogens could have primed development of metabolic machineries for their degradation, especially in microorganisms. Among these, a special group of anaerobic microorganisms was discovered that could conserve energy by reducing organohalogens as terminal electron acceptor in a process termed organohalide respiration. Originally discovered in a quest for biodegradation of anthropogenic organohalogens, these organohalide-respiring bacteria (OHRB) were soon found to reside in pristine environments, such as the deep subseafloor and Arctic tundra soil with limited/no connections to anthropogenic activities. As such, accumulating evidence suggests an important role of OHRB in local natural halogen cycles, presumably taking advantage of natural organohalogens. In this minireview, we integrate current knowledge regarding the natural origin and occurrence of industrially important organohalogens and the evolution and spread of OHRB, and describe potential implications for natural halogen and carbon cycles.
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Affiliation(s)
- Siavash Atashgahi
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, Wageningen 6708 WE, The Netherlands
| | - Max M Häggblom
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA
| | - Hauke Smidt
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, Wageningen 6708 WE, The Netherlands
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13
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Wever R, Barnett P. Vanadium Chloroperoxidases: The Missing Link in the Formation of Chlorinated Compounds and Chloroform in the Terrestrial Environment? Chem Asian J 2017; 12:1997-2007. [DOI: 10.1002/asia.201700420] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 05/30/2017] [Indexed: 01/02/2023]
Affiliation(s)
- Ron Wever
- Van't Hoff Institute for Molecular Sciences; University of Amsterdam; Science Park 904 1098 XH Amsterdam The Netherlands
| | - Phil Barnett
- Department of Anatomy; Embryology and Physiology; Academic Medical Center Amsterdam; Meibergdreef 15 1105 AZ Amsterdam The Netherlands
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Kellner S, DeMott MS, Cheng CP, Russell BS, Cao B, You D, Dedon PC. Oxidation of phosphorothioate DNA modifications leads to lethal genomic instability. Nat Chem Biol 2017; 13:888-894. [PMID: 28604692 PMCID: PMC5577368 DOI: 10.1038/nchembio.2407] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 03/30/2017] [Indexed: 12/12/2022]
Abstract
Genomic modification with sulfur as phosphorothioate (PT) is widespread among prokaryotes, including human pathogens. Apart from its physiological functions, the redox and nucleophilic properties of PT sulfur suggest effects on bacterial fitness in stressful environments. Here we show that PTs are dynamic and labile DNA modifications that cause genomic instability during oxidative stress. Using coupled isotopic labeling-mass spectrometry, we observed sulfur replacement in PTs at a rate of ~2%/h in unstressed Escherichia coli and Salmonella enterica. While PT levels were unaffected by exposure to hydrogen peroxide (H2O2) or hypochlorous acid (HOCl), PT turnover increased to 3.8–10%/h for HOCl and was unchanged for H2O2, consistent with repair of HOCl-induced sulfur damage. PT-dependent HOCl sensitivity extended to cytotoxicity and DNA strand-breaks, which occurred at orders-of-magnitude lower doses of HOCl than H2O2. The genotoxicity of HOCl in PT-containing bacteria suggests reduced fitness in competition with HOCl-producing organisms and during human infections.
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Affiliation(s)
- Stefanie Kellner
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Michael S DeMott
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Ching Pin Cheng
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Brandon S Russell
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Bo Cao
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Delin You
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Peter C Dedon
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.,Singapore-MIT Alliance for Research and Technology, Singapore
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15
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Weigold P, El-Hadidi M, Ruecker A, Huson DH, Scholten T, Jochmann M, Kappler A, Behrens S. A metagenomic-based survey of microbial (de)halogenation potential in a German forest soil. Sci Rep 2016; 6:28958. [PMID: 27353292 PMCID: PMC4926216 DOI: 10.1038/srep28958] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 06/13/2016] [Indexed: 11/16/2022] Open
Abstract
In soils halogens (fluorine, chlorine, bromine, iodine) are cycled through the transformation of inorganic halides into organohalogen compounds and vice versa. There is evidence that these reactions are microbially driven but the key enzymes and groups of microorganisms involved are largely unknown. Our aim was to uncover the diversity, abundance and distribution of genes encoding for halogenating and dehalogenating enzymes in a German forest soil by shotgun metagenomic sequencing. Metagenomic libraries of three soil horizons revealed the presence of genera known to be involved in halogenation and dehalogenation processes such as Bradyrhizobium or Pseudomonas. We detected a so far unknown diversity of genes encoding for (de)halogenating enzymes in the soil metagenome including specific and unspecific halogenases as well as metabolic and cometabolic dehalogenases. Genes for non-heme, no-metal chloroperoxidases and haloalkane dehalogenases were the most abundant halogenase and dehalogenase genes, respectively. The high diversity and abundance of (de)halogenating enzymes suggests a strong microbial contribution to natural halogen cycling. This was also confirmed in microcosm experiments in which we quantified the biotic formation of chloroform and bromoform. Knowledge on microorganisms and genes that catalyze (de)halogenation reactions is critical because they are highly relevant to industrial biotechnologies and bioremediation applications.
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Affiliation(s)
- Pascal Weigold
- Geomicrobiology, Center for Applied Geosciences, University of
Tuebingen, Germany
| | - Mohamed El-Hadidi
- Algorithms in Bioinformatics, Center for Bioinformatics,
University of Tuebingen, Germany
| | - Alexander Ruecker
- Geomicrobiology, Center for Applied Geosciences, University of
Tuebingen, Germany
| | - Daniel H. Huson
- Algorithms in Bioinformatics, Center for Bioinformatics,
University of Tuebingen, Germany
| | - Thomas Scholten
- Soil Science and Geomorphology, Geography, University of
Tuebingen, Germany
| | - Maik Jochmann
- Instrumental Analytical Chemistry, Faculty of Chemistry,
University of Duisburg-Essen, Germany
| | - Andreas Kappler
- Geomicrobiology, Center for Applied Geosciences, University of
Tuebingen, Germany
| | - Sebastian Behrens
- Department of Civil, Environmental, and Geo- Engineering,
University of Minnesota, MN, USA
- BioTechnology Institute, University of Minnesota,
MN, USA
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16
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Montelius M, Thiry Y, Marang L, Ranger J, Cornelis JT, Svensson T, Bastviken D. Experimental evidence of large changes in terrestrial chlorine cycling following altered tree species composition. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:4921-8. [PMID: 25811074 DOI: 10.1021/acs.est.5b00137] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Organochlorine molecules (Clorg) are surprisingly abundant in soils and frequently exceed chloride (Cl(-)) levels. Despite the widespread abundance of Clorg and the common ability of microorganisms to produce Clorg, we lack fundamental knowledge about how overall chlorine cycling is regulated in forested ecosystems. Here we present data from a long-term reforestation experiment where native forest was cleared and replaced with five different tree species. Our results show that the abundance and residence times of Cl(-) and Clorg after 30 years were highly dependent on which tree species were planted on the nearby plots. Average Cl(-) and Clorg content in soil humus were higher, at experimental plots with coniferous trees than in those with deciduous trees. Plots with Norway spruce had the highest net accumulation of Cl(-) and Clorg over the experiment period, and showed a 10 and 4 times higher Cl(-) and Clorg storage (kg ha(-1)) in the biomass, respectively, and 7 and 9 times higher storage of Cl(-) and Clorg in the soil humus layer, compared to plots with oak. The results can explain why local soil chlorine levels are frequently independent of atmospheric deposition, and provide opportunities for improved modeling of chlorine distribution and cycling in terrestrial ecosystems.
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Affiliation(s)
- Malin Montelius
- †Department of Thematic Studies-Environmental Change, Linköping University, SE-581 83, Linköping, Sweden
| | - Yves Thiry
- ‡Andra, Research and Development Division, Parc de la Croix Blanche, 1/7 rue Jean Monnet, 92298 Châtenay-Malabry Cedex, France
| | - Laura Marang
- §EDF, Laboratoire National d'Hydraulique et Environnement, 78401 Chatou, France
| | - Jacques Ranger
- ∥Biogéochimie des écosystèmes forestiers, INRA Centre de Nancy, 54280 Champenoux, France
| | - Jean-Thomas Cornelis
- ⊥Soil Science Lab, Earth and Life Institute - Environmental Sciences, Université Catholique de Louvain, Croix du Sud 2/10, 1348 Louvain-la-Neuve, Belgium
| | - Teresia Svensson
- †Department of Thematic Studies-Environmental Change, Linköping University, SE-581 83, Linköping, Sweden
| | - David Bastviken
- †Department of Thematic Studies-Environmental Change, Linköping University, SE-581 83, Linköping, Sweden
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17
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Breider F, Albers CN. Formation mechanisms of trichloromethyl-containing compounds in the terrestrial environment: a critical review. CHEMOSPHERE 2015; 119:145-154. [PMID: 24974224 DOI: 10.1016/j.chemosphere.2014.05.080] [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: 01/16/2014] [Revised: 05/14/2014] [Accepted: 05/28/2014] [Indexed: 06/03/2023]
Abstract
Natural trichloromethyl compounds present in the terrestrial environment are important contributors to chlorine in the lower atmosphere and may be also a cause for concern when high concentrations are detected in soils and groundwater. During the last decade our knowledge of the mechanisms involved in the formation of these compounds has grown. This critical review summarizes our current understanding and uncertainties on the mechanisms leading to the formation of natural trichloromethyl compounds. The objective of the review is to gather information regarding the natural processes that lead to the formation of trichloromethyl compounds and then to compare these mechanisms with the much more comprehensive literature on the reactions occurring during chemical chlorination of organic material. It turns out that the reaction mechanisms during chemical chlorination are likely to be similar to those occurring naturally and that significant knowledge may therefore be transferred between the scientific disciplines of chemical chlorination and natural organohalogens. There is however still a need for additional research before we understand fully the mechanisms occurring during the formation of natural trichloromethyl compounds and open questions and future research needs are identified in the last part of the review.
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Affiliation(s)
- Florian Breider
- Tokyo Institute of Technology, Department of Environmental Chemistry and Engineering, Nagatsuta 4259, Midori-ku, Yokohama 226-8502, Kanagawa, Japan.
| | - Christian Nyrop Albers
- Geological Survey of Denmark and Greenland, Department of Geochemistry, Øster Voldgade 10, DK-1350 Copenhagen, Denmark; Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, DK-1350 Copenhagen, Denmark
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18
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Parker BW, Schwessinger EA, Jakob U, Gray MJ. The RclR protein is a reactive chlorine-specific transcription factor in Escherichia coli. J Biol Chem 2013; 288:32574-32584. [PMID: 24078635 DOI: 10.1074/jbc.m113.503516] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Reactive chlorine species (RCS) such as hypochlorous acid are powerful antimicrobial oxidants. Used extensively for disinfection in household and industrial settings (i.e. as bleach), RCS are also naturally generated in high quantities during the innate immune response. Bacterial responses to RCS are complex and differ substantially from the well characterized responses to other physiologically relevant oxidants, like peroxide or superoxide. Several RCS-sensitive transcription factors have been identified in bacteria, but most of them respond to multiple stressors whose damaging effects overlap with those of RCS, including reactive oxygen species and electrophiles. We have now used in vivo genetic and in vitro biochemical methods to identify and demonstrate that Escherichia coli RclR (formerly YkgD) is a redox-regulated transcriptional activator of the AraC family, whose highly conserved cysteine residues are specifically sensitive to oxidation by RCS. Oxidation of these cysteines leads to strong, highly specific activation of expression of genes required for survival of RCS stress. These results demonstrate the existence of a widely conserved bacterial regulon devoted specifically to RCS resistance.
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Affiliation(s)
- Benjamin W Parker
- From the Department of Molecular, Cellular, and Developmental Biology
| | | | - Ursula Jakob
- From the Department of Molecular, Cellular, and Developmental Biology; the Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan 48109.
| | - Michael J Gray
- From the Department of Molecular, Cellular, and Developmental Biology.
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19
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Aeppli C, Bastviken D, Andersson P, Gustafsson O. Chlorine isotope effects and composition of naturally produced organochlorines from chloroperoxidases, flavin-dependent halogenases, and in forest soil. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:6864-6871. [PMID: 23320408 DOI: 10.1021/es3037669] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The use of stable chlorine isotopic signatures (δ(37)Cl) of organochlorine compounds has been suggested as a tool to determine both their origins and transformations in the environment. Here we investigated the δ(37)Cl fractionation of two important pathways for enzymatic natural halogenation: chlorination by chloroperoxidase (CPO) and flavin-dependent halogenases (FDH). Phenolic products of CPO were highly (37)Cl depleted (δ(37)Cl = -12.6 ± 0.9‰); significantly more depleted than all known industrially produced organochlorine compounds (δ(37)Cl = -7 to +6‰). In contrast, four FDH products did not exhibit any observable isotopic shifts (δ(37)Cl = -0.3 ± 0.6‰). We attributed the different isotopic effect to the distinctly different chlorination mechanisms employed by the two enzymes. Furthermore, the δ(37)Cl in bulk organochlorines extracted from boreal forest soils were only slightly depleted in (37)Cl relative to inorganic Cl. In contrast to previous suggestions that CPO plays a key role in production of soil organochlorines, this observation points to the additional involvement of either other chlorination pathways, or that dechlorination of naturally produced organochlorines can neutralize δ(37)Cl shifts caused by CPO chlorination. Overall, this study demonstrates that chlorine isotopic signatures are highly useful to understand sources and cycling of organochlorines in nature. Furthermore, this study presents δ(37)Cl values of FDH products as well of bulk organochlorines extracted from pristine forest soil for the first time.
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Affiliation(s)
- Christoph Aeppli
- Department of Applied Environmental Science (ITM), Stockholm University, Sweden.
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20
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Abstract
Hypochlorous acid (HOCl), the active ingredient of household bleach, is the most common disinfectant in medical, industrial, and domestic use and plays an important role in microbial killing in the innate immune system. Given the critical importance of the antimicrobial properties of chlorine to public health, it is surprising how little is known about the ways in which bacteria sense and respond to reactive chlorine species (RCS). Although the literature on bacterial responses to reactive oxygen species (ROS) is enormous, work addressing bacterial responses to RCS has begun only recently. Transcriptomic and proteomic studies now provide new insights into how bacteria mount defenses against this important class of antimicrobial compounds. In this review, we summarize the current knowledge, emphasizing the overlaps between RCS stress responses and other more well-characterized bacterial defense systems, and identify outstanding questions that represent productive avenues for future research.
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Affiliation(s)
- Michael J Gray
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1048; , ,
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21
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Bengtson P, Bastviken D, Oberg G. Possible roles of reactive chlorine II: assessing biotic chlorination as a way for organisms to handle oxygen stress. Environ Microbiol 2012; 15:991-1000. [PMID: 22712445 DOI: 10.1111/j.1462-2920.2012.02807.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Natural formation of organically bound chlorine is extensive in many environments. The enzymes associated with the formation of chlorinated organic matter are produced by a large variety of organisms. Little is known about the ecological role of the process, the key question being: why do microorganisms promote chlorination of organic matter? In a recent paper we discuss whether organic matter chlorination may be a result of antagonistic interactions among microorganisms. In the present paper we evaluate whether extracellular microbial formation of reactive chlorine may be used as a defence against oxygen stress, and we discuss whether this process is likely to contribute to the formation of chlorinated organic matter. Our analysis suggests that periodic exposure to elevated concentrations of reactive oxygen species is a common denominator among the multitude of organisms that are able to enzymatically catalyse formation of reactive chlorine. There is also some evidence suggesting that the production of such enzymes in algae and bacteria is induced by oxygen stress. The relative contribution from this process to the extensive formation of chlorinated organic matter in natural environments remains to be empirically assessed.
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Affiliation(s)
- Per Bengtson
- Department of Biology - Microbial Ecology, Lund University, The Ecology Building, Lund SE-223 62, Sweden
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22
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Gustavsson M, Karlsson S, Oberg G, Sandén P, Svensson T, Valinia S, Thiry Y, Bastviken D. Organic matter chlorination rates in different boreal soils: the role of soil organic matter content. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:1504-10. [PMID: 22191661 DOI: 10.1021/es203191r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Transformation of chloride (Cl(-)) to organic chlorine (Cl(org)) occurs naturally in soil but it is poorly understood how and why transformation rates vary among environments. There are still few measurements of chlorination rates in soils, even though formation of Cl(org) has been known for two decades. In the present study, we compare organic matter (OM) chlorination rates, measured by (36)Cl tracer experiments, in soils from eleven different locations (coniferous forest soils, pasture soils and agricultural soils) and discuss how various environmental factors effect chlorination. Chlorination rates were highest in the forest soils and strong correlations were seen with environmental variables such as soil OM content and Cl(-) concentration. Data presented support the hypothesis that OM levels give the framework for the soil chlorine cycling and that chlorination in more organic soils over time leads to a larger Cl(org) pool and in turn to a high internal supply of Cl(-) upon dechlorination. This provides unexpected indications that pore water Cl(-) levels may be controlled by supply from dechlorination processes and can explain why soil Cl(-) locally can be more closely related to soil OM content and the amount organically bound chlorine than to Cl(-) deposition.
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Affiliation(s)
- Malin Gustavsson
- Department of Thematic Studies, Water and Environmental Studies, Linköping University, 58183 Linköping, Sweden.
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23
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Redon PO, Abdelouas A, Bastviken D, Cecchini S, Nicolas M, Thiry Y. Chloride and organic chlorine in forest soils: storage, residence times, and influence of ecological conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:7202-8. [PMID: 21761932 DOI: 10.1021/es2011918] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Recent studies have shown that extensive chlorination of natural organic matter significantly affects chlorine (Cl) residence time in soils. This natural biogeochemical process must be considered when developing the conceptual models used as the basis for safety assessments regarding the potential health impacts of 36-chlorine released from present and planned radioactive waste disposal facilities. In this study, we surveyed 51 French forested areas to determine the variability in chlorine speciation and storage in soils. Concentrations of total chlorine (Cl(tot)) and organic chlorine (Cl(org)) were determined in litterfall, forest floor and mineral soil samples. Cl(org) constituted 11-100% of Cl(tot), with the highest concentrations being found in the humus layer (34-689 mg Cl(org) kg(-1)). In terms of areal storage (53 - 400 kg Cl(org) ha(-1)) the mineral soil dominated due to its greater thickness (40 cm). Cl(org) concentrations and estimated retention of organochlorine in the humus layer were correlated with Cl input, total Cl concentration, organic carbon content, soil pH and the dominant tree species. Cl(org) concentration in mineral soil was not significantly influenced by the studied environmental factors, however increasing Cl:C ratios with depth could indicate selective preservation of chlorinated organic molecules. Litterfall contributions of Cl were significant but generally minor compared to other fluxes and stocks. Assuming steady-state conditions, known annual wet deposition and measured inventories in soil, the theoretical average residence time calculated for total chlorine (inorganic (Cl(in)) and organic) was 5-fold higher than that estimated for Cl(in) alone. Consideration of the Cl(org) pool is therefore clearly important in studies of overall Cl cycling in terrestrial ecosystems.
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Affiliation(s)
- Paul-Olivier Redon
- Andra, Research and Development Division, 1-7 rue Jean Monnet, 92298 Châtenay-Malabry, France
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24
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Ghosh S, Cremers CM, Jakob U, Love NG. Chlorinated phenols control the expression of the multidrug resistance efflux pump MexAB-OprM in Pseudomonas aeruginosa by interacting with NalC. Mol Microbiol 2011; 79:1547-56. [PMID: 21231970 DOI: 10.1111/j.1365-2958.2011.07544.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
NalC is a TetR type regulator that represses the multidrug efflux pump MexAB-OprM in Pseudomonas aeruginosa. Here we explain the mechanism of NalC-mediated regulation of MexAB-OprM. We show that NalC non-covalently binds chlorinated phenols and chemicals containing chlorophenol side-chains such as triclosan. NalC-chlorinated phenol binding results in its dissociation from promoter DNA and upregulation of NalC's downstream targets, including the MexR antirepressor ArmR. ArmR upregulation and MexR-ArmR complex formation have previously been shown to upregulate MexAB-OprM. In vivo mexB and armR expression analyses were used to corroborate in vitro NalC-chlorinated phenol binding. We also show that the interaction between chlorinated phenols and NalC is reversible, such that removal of these chemicals restored NalC promoter DNA binding. Thus, the NalC-chlorinated phenol interaction is likely a pertinent physiological mechanism that P. aeruginosa uses to control expression of the MexAB-OprM efflux pump.
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Affiliation(s)
- Sudeshna Ghosh
- Department of Civil and Environmental Engineering, University of Michigan, 2350 Hayward Street, 2340 GG Brown, Ann Arbor, MI 48109-2125, USA
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25
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Hofrichter M, Ullrich R, Pecyna MJ, Liers C, Lundell T. New and classic families of secreted fungal heme peroxidases. Appl Microbiol Biotechnol 2010; 87:871-97. [PMID: 20495915 DOI: 10.1007/s00253-010-2633-0] [Citation(s) in RCA: 333] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 04/14/2010] [Accepted: 04/14/2010] [Indexed: 01/15/2023]
Abstract
Heme-containing peroxidases secreted by fungi are a fascinating group of biocatalysts with various ecological and biotechnological implications. For example, they are involved in the biodegradation of lignocelluloses and lignins and participate in the bioconversion of other diverse recalcitrant compounds as well as in the natural turnover of humic substances and organohalogens. The current review focuses on the most recently discovered and novel types of heme-dependent peroxidases, aromatic peroxygenases (APOs), and dye-decolorizing peroxidases (DyPs), which catalyze remarkable reactions such as peroxide-driven oxygen transfer and cleavage of anthraquinone derivatives, respectively, and represent own separate peroxidase superfamilies. Furthermore, several aspects of the "classic" fungal heme-containing peroxidases, i.e., lignin, manganese, and versatile peroxidases (LiP, MnP, and VP), phenol-oxidizing peroxidases as well as chloroperoxidase (CPO), are discussed against the background of recent scientific developments.
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Affiliation(s)
- Martin Hofrichter
- Department of Environmental Biotechnology, International Graduate School of Zittau, Markt 23, 02763, Zittau, Germany.
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26
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Barakat H, Spielvogel A, Hassan M, El-Desouky A, El-Mansy H, Rath F, Meyer V, Stahl U. The antifungal protein AFP from Aspergillus giganteus prevents secondary growth of different Fusarium species on barley. Appl Microbiol Biotechnol 2010; 87:617-24. [PMID: 20217075 DOI: 10.1007/s00253-010-2508-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 02/09/2010] [Accepted: 02/10/2010] [Indexed: 10/19/2022]
Abstract
Secondary growth is a common post-harvest problem when pre-infected crops are attacked by filamentous fungi during storage or processing. Several antifungal approaches are thus pursued based on chemical, physical, or bio-control treatments; however, many of these methods are inefficient, affect product quality, or cause severe side effects on the environment. A protein that can potentially overcome these limitations is the antifungal protein AFP, an abundantly secreted peptide of the filamentous fungus Aspergillus giganteus. This protein specifically and at low concentrations disturbs the integrity of fungal cell walls and plasma membranes but does not interfere with the viability of other pro- and eukaryotic systems. We thus studied in this work the applicability of AFP to efficiently prevent secondary growth of filamentous fungi on food stuff and chose, as a case study, the malting process where naturally infested raw barley is often to be used as starting material. Malting was performed under lab scale conditions as well as in a pilot plant, and AFP was applied at different steps during the process. AFP appeared to be very efficient against the main fungal contaminants, mainly belonging to the genus Fusarium. Fungal growth was completely blocked after the addition of AFP, a result that was not observed for traditional disinfectants such as ozone, hydrogen peroxide, and chlorine dioxide. We furthermore detected reduced levels of the mycotoxin deoxynivalenol after AFP treatment, further supporting the fungicidal activity of the protein. As AFP treatments did not compromise any properties and qualities of the final products malt and wort, we consider the protein as an excellent biological alternative to combat secondary growth of filamentous fungi on food stuff.
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Affiliation(s)
- Hassan Barakat
- Department of Microbiology and Genetics, Institute of Biotechnology, Berlin University of Technology, Gustav-Meyer-Allee 25, 13355, Berlin, Germany
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27
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Taş N, van Eekert MHA, de Vos WM, Smidt H. The little bacteria that can - diversity, genomics and ecophysiology of 'Dehalococcoides' spp. in contaminated environments. Microb Biotechnol 2009; 3:389-402. [PMID: 21255338 PMCID: PMC3815806 DOI: 10.1111/j.1751-7915.2009.00147.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The fate and persistence of chlorinated organics in the environment have been a concern for the past 50 years. Industrialization and extensive agricultural activities have led to the accumulation of these pollutants in the environment, while their adverse impact on various ecosystems and human health also became evident. This review provides an update on the current knowledge of specialized anaerobic bacteria, namely ‘Dehalococcoides’ spp., which are dedicated to the transformation of various chlorinated organic compounds via reductive dechlorination. Advances in microbiology and molecular techniques shed light into the diversity and functioning of Dehalococcoides spp. in several different locations. Recent genome sequencing projects revealed a large number of genes that are potentially involved in reductive dechlorination. Molecular approaches towards analysis of diversity and expression especially of reductive dehalogenase‐encoding genes are providing a growing body of knowledge on biodegradative pathways active in defined pure and mixed cultures as well as directly in the environment. Moreover, several successful field cases of bioremediation strengthen the notion of dedicated degraders such as Dehalococcoides spp. as key players in the restoration of contaminated environments.
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Affiliation(s)
- Neslihan Taş
- Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, the Netherlands
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