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Qiao J, Zhao Z, Zhou Z, Wu D. Enhanced hydrodechlorination of 4-chlorophenol through carboxymethylcellulose-modified Pd/Fe nanosuspension synthesized by one-step methods. CHEMOSPHERE 2024; 356:141857. [PMID: 38570045 DOI: 10.1016/j.chemosphere.2024.141857] [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: 11/30/2023] [Revised: 03/01/2024] [Accepted: 03/28/2024] [Indexed: 04/05/2024]
Abstract
Palladized iron (Pd/Fe) represents one of the most common modification strategies for nanoscale zero-valent iron (nZVI). Most studies prepared Pd/Fe by reducing iron salts and depositing Pd species on the surface of pre-synthesized nZVI, which can be called the two-step method. In this study, we proposed a one-step method to obtain Pd/Fe by the concurrent formation of Fe0 and Pd0 and investigated the effects of these two methods on 4-chlorophenol (4-CP) removal, with carboxymethylcellulose (CMC) coated as a surface modifier. Results indicated that the one-step method, not only streamlined the synthesis process, but also Pd/Fe-CMCone-step, synthesized by it, exhibited a higher 4-CP removal rate (97.9%) compared to the two-step method material Pd/Fe-CMCtwo-step (82.4%). Electrochemical analyses revealed that the enhanced activity of Pd/Fe-CMCone-step was attributed to its higher electron transfer efficiency and more available reactive species, active adsorbed hydrogen species (Hads*). Detection of intermediate products demonstrated that, under the influence of Pd/Fe-CMCone-step, the main route of 4-CP was through hydrodechlorination (HDC) to form phenol and H* was the main active specie, supported by EPR tests, quenching experiments and product analysis. Additionally, the effects of initial 4-CP concentration, initial pH, O2 concentration, anions such as Cl-, SO42-, HCO3-, and humic acid (HA) were also investigated. In conclusion, the results of this study suggest that Pd/Fe-CMCone-step, synthesized through the one-step method, is a convenient and efficient nZVI-modifying material suitable for the HDC of chlorinated organic compounds.
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Affiliation(s)
- Juan Qiao
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Key Laboratory of Urban Water Supply, Water Saving and Water Environment Governance in the Yangtze River Delta of Ministry of Water Resources, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai, 200092, China
| | - Zhenyu Zhao
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Key Laboratory of Urban Water Supply, Water Saving and Water Environment Governance in the Yangtze River Delta of Ministry of Water Resources, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai, 200092, China
| | - Zhengwei Zhou
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Key Laboratory of Urban Water Supply, Water Saving and Water Environment Governance in the Yangtze River Delta of Ministry of Water Resources, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai, 200092, China
| | - Deli Wu
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Key Laboratory of Urban Water Supply, Water Saving and Water Environment Governance in the Yangtze River Delta of Ministry of Water Resources, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai, 200092, China.
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2
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Lin M, Pan C, Qian C, Tang F, Zhao S, Guo J, Zhang Y, Song J, Rittmann BE. Core taxa, co-occurrence pattern, diversity, and metabolic pathways contributing to robust anaerobic biodegradation of chlorophenol. ENVIRONMENTAL RESEARCH 2024; 241:117591. [PMID: 37926226 DOI: 10.1016/j.envres.2023.117591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/28/2023] [Accepted: 11/02/2023] [Indexed: 11/07/2023]
Abstract
It is hard to achieve robustness in anaerobic biodegradation of trichlorophenol (TCP). We hypothesized that specific combinations of environmental factors determine phylogenetic diversity and play important roles in the decomposition and stability of TCP-biodegrading bacteria. The anaerobic bioreactor was operated at 35 °C (H condition) or 30 °C (L condition) and mainly fed with TCP (from 28 μM to 180 μM) and organic material. Metagenome sequencing was combined with 16S rRNA gene amplicon sequencing for the microbial community analysis. The results exhibited that the property of robustness occurred in specific conditions. The corresponding co-occurrence and diversity patterns suggest high collectivization, degree and evenness for robust communities. Two types of core functional taxa were recognized: dechlorinators (unclassified Anaerolineae, Thermanaerothrix and Desulfovibrio) and ring-opening members (unclassified Proteobacteria, Methanosarcina, Methanoperedens, and Rubrobacter). The deterministic process of the expansion of niche of syntrophic bacteria at higher temperatures was confirmed. The reductive and hydrolytic dechlorination mechanisms jointly lead to C-Cl bond cleavage. H ultimately adapted to the stress of high TCP loading, with more abundant ring-opening enzyme (EC 3.1.1.45, ∼55%) and hydrolytic dechlorinase (EC 3.8.1.5, 26.5%) genes than L (∼47%, 10.5%). The functional structure (based on KEGG) in H was highly stable despite the high loading of TCP (up to 60 μM), but not in L. Furthermore, an unknown taxon with multiple functions (dechlorinating and ring-opening) was found based on genetic sequencing; its functional contribution of EC 3.8.1.5 in H (26.5%) was higher than that in L (10.5%), and it possessed a new metabolic pathway for biodegradation of halogenated aromatic compounds. This new finding is supplementary to the robust mechanisms underlying organic chlorine biodegradation, which can be used to support the engineering, regulation, and design of synthetic microbiomes.
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Affiliation(s)
- Ming Lin
- School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai, 200234, PR China; Yangtze River Delta Urban Wetland Ecosystem National Field Scientific Observation and Research Station, Shanghai, 200234, PR China
| | - Chenhui Pan
- School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai, 200234, PR China; Yangtze River Delta Urban Wetland Ecosystem National Field Scientific Observation and Research Station, Shanghai, 200234, PR China
| | - Chenyi Qian
- School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai, 200234, PR China; Yangtze River Delta Urban Wetland Ecosystem National Field Scientific Observation and Research Station, Shanghai, 200234, PR China
| | - Fei Tang
- School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai, 200234, PR China; Yangtze River Delta Urban Wetland Ecosystem National Field Scientific Observation and Research Station, Shanghai, 200234, PR China
| | - Siwen Zhao
- School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai, 200234, PR China; Yangtze River Delta Urban Wetland Ecosystem National Field Scientific Observation and Research Station, Shanghai, 200234, PR China
| | - Jun Guo
- School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai, 200234, PR China; Department of Environmental Science and Engineering, Fudan University, Shanghai, 200238, PR China
| | - Yongming Zhang
- School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai, 200234, PR China; Yangtze River Delta Urban Wetland Ecosystem National Field Scientific Observation and Research Station, Shanghai, 200234, PR China
| | - Jiaxiu Song
- School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai, 200234, PR China; Yangtze River Delta Urban Wetland Ecosystem National Field Scientific Observation and Research Station, Shanghai, 200234, PR China.
| | - Bruce E Rittmann
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ, 85287-5701, USA
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3
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Fang L, Zhou Y, Chen T, Geng Y, Li Z, Zha W, Shi T, Hua R. Efficient biodegradation characteristics and detoxification pathway of organophosphorus insecticide profenofos via Cupriavidus nantongensis X1 T and enzyme OpdB. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 862:160782. [PMID: 36513234 DOI: 10.1016/j.scitotenv.2022.160782] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/30/2022] [Accepted: 12/05/2022] [Indexed: 06/17/2023]
Abstract
Profenofos residues in the environment pose a high risk to mammals and non-target organisms. In this study, the biodegradation and detoxification of profenofos in an efficient degrading strain, Cupriavidus nantongensis X1T, was investigated. Strain X1T could degrade 88.82 % of 20 mg/L profenofos in 48 h. The optimum temperature and inoculation amount of strain X1T for the degradation of profenofos were 30-37 °C and 20 % (V/V), respectively. Metabolic pathway analysis showed that strain X1T could degrade both profenofos and its main metabolite 4-bromo-2-chlorophenol. Metabolite toxicity analysis results showed that dehalogenation was the main detoxification step in profenofos biodegradation. The key gene and enzyme for profenofos degradation in strain X1T were also explored. RT-qPCR shows that organophosphorus hydrolase (OpdB) was the key enzyme to control the hydrolysis process in strain X1T. The purified enzyme OpdB in vitro had the same degradation characteristics as strain X1T. Divalent metal cations could significantly enhance the hydrolysis activity of strain X1T and enzyme OpdB. Meanwhile, strain X1T could degrade 60.89 % of 20 mg/L profenofos in actual field soil within 72 h. This study provides an efficient biological resource for the remediation of profenofos residual pollution in the environment.
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Affiliation(s)
- Liancheng Fang
- Anhui Provincial Key Laboratory for Quality and Safety of Agri-Products, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China; Institute for Green Development, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Yujing Zhou
- Anhui Provincial Key Laboratory for Quality and Safety of Agri-Products, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Tianming Chen
- Anhui Provincial Key Laboratory for Quality and Safety of Agri-Products, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Yuehan Geng
- Anhui Provincial Key Laboratory for Quality and Safety of Agri-Products, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Zijing Li
- Anhui Provincial Key Laboratory for Quality and Safety of Agri-Products, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Wei Zha
- Anhui Provincial Key Laboratory for Quality and Safety of Agri-Products, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Taozhong Shi
- Anhui Provincial Key Laboratory for Quality and Safety of Agri-Products, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Rimao Hua
- Anhui Provincial Key Laboratory for Quality and Safety of Agri-Products, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China; Institute for Green Development, Anhui Agricultural University, Hefei, Anhui 230036, China.
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4
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Dorner M, Lokesh S, Yang Y, Behrens S. Biochar-mediated abiotic and biotic degradation of halogenated organic contaminants - A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 852:158381. [PMID: 36055499 DOI: 10.1016/j.scitotenv.2022.158381] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/23/2022] [Accepted: 08/25/2022] [Indexed: 06/15/2023]
Abstract
Prevailing global increases in population, urbanization, and agricultural production are causing increased pressures on water resources, especially as the use of chemicals in agriculture, industry, and medicine provide new challenges for water treatment and reuse. Organohalogen compounds are persistent contaminants that often evade current wastewater treatment technologies, resulting in their accumulation in the environment and posing a serious threat to ecosystem health. Recent advances in understanding pyrogenic carbons as electron shuttling and storing materials have exposed their potential for enhancing the dehalogenation and overall degradation of organohalide contaminants in soil, sediment, surface water, and wastewater systems. Biochar is a porous carbonaceous material produced during the thermochemical decomposition of biomass feedstock in the presence of little or no oxygen (pyrolysis). Interest in biochar for application towards environmental remediation is largely based on its three distinct benefits: I) carbon sequestration to offset greenhouse gas emissions, II) adsorption of (in-) organic contaminants and nutrients, and III) a strong electron exchange capacity. Due to the innate complexity of biochar materials, several electron transfer mechanisms exist by which biochar may mediate contaminant degradation. These electron transfer pathways include electron-accepting and donating cycles through redox-active functional groups and direct electron transfer via conductive carbon matrices. These mechanisms are responsible for biochar's participation in multiple redox-driven biogeochemical transformations with proven consequences for effective organohalogen remediation. This literature review summarizes the current knowledge on the mechanisms and processes through which biochar can directly or indirectly mediate the transformation of organohalogen compounds under various environmental conditions. Perspectives and research directions for future application of biochars for targeted remediation strategies are also discussed.
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Affiliation(s)
- Mariah Dorner
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Srinidhi Lokesh
- Department of Civil and Environmental Engineering, University of Nevada, Reno, NV, USA
| | - Yu Yang
- Department of Civil and Environmental Engineering, University of Nevada, Reno, NV, USA
| | - Sebastian Behrens
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis, MN, USA; BioTechnology Institute, University of Minnesota, St. Paul, MN, USA.
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Kato H, Sakai K, Itoh S, Iwata N, Ito M, Hori M, Kato M, Shimizu M. Enhanced Bioremediation of 4-Chlorophenol by Electrically Neutral Reactive Species Generated from Nonthermal Atmospheric-Pressure Plasma. ACS OMEGA 2022; 7:16197-16203. [PMID: 35571825 PMCID: PMC9097213 DOI: 10.1021/acsomega.2c01615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 04/18/2022] [Indexed: 06/15/2023]
Abstract
4-Chlorophenol (4-CP) is a chlorinated aromatic compound with broad industrial applications. It is released into the environment as an industrial byproduct and is highly resistant to biodegradation. Pseudomonas sp. in the environment and activated sludge are used for 4-CP bioremediation; however, the degradation of 4-CP takes a long time. Consequently, the toxicity of 4-CP is a major barrier to its bioremediation. In this study, we investigated the synergistic effect of electrically neutral reactive species on the bacterial bioremediation of 4-CP. Our results showed that the concentration of 4-CP decreased from 2.0 to 0.137 mM and that it was converted to 4-chlorocatechol (4-CC; 0.257 mM), 4-chlororesorcinol (0.157 mM), hydroquinone (0.155 mM), and trihydroxy chlorobenzene and their respective ring-cleaved products following irradiation of neutral reactive species. These compounds were less toxic than 4-CP, except for 4-CC, which reduced the toxicity of 4-CP to Pseudomonas putida. When the neutral reactive species-treated 4-CP fraction was added to P. putida cultured in a synthetic sewage medium for 48 h, the 4-CP concentration was reduced to 0.017 mM, whereas nontreated 4-CP (2.0 mM) was hardly degraded by P. putida. These results suggest that the biodegradation of 4-CP can be efficiently improved by combining irradiation of neutral reactive species with microbial treatment. The irradiation of neutral reactive species of environmental pollutants may additionally lead to further improvements in bioremediation processes.
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Affiliation(s)
- Hiroyuki Kato
- Faculty
of Agriculture, Meijo University, Nagoya 468-8502, Aichi, Japan
| | - Kiyota Sakai
- Faculty
of Agriculture, Meijo University, Nagoya 468-8502, Aichi, Japan
| | - Shou Itoh
- Faculty
of Agriculture, Meijo University, Nagoya 468-8502, Aichi, Japan
| | - Naoyuki Iwata
- Department
of Electronics Engineering, Nagoya University, Nagoya 464-8603, Aichi, Japan
| | - Masafumi Ito
- Faculty
of Science and Technology, Meijo University, Nagoya 468-8502, Aichi, Japan
| | - Masaru Hori
- Center
for Low-temperature Plasma Sciences, Nagoya
University, Nagoya 464-8603, Aichi, Japan
| | - Masashi Kato
- Faculty
of Agriculture, Meijo University, Nagoya 468-8502, Aichi, Japan
| | - Motoyuki Shimizu
- Faculty
of Agriculture, Meijo University, Nagoya 468-8502, Aichi, Japan
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6
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Degradation of 2,6-dicholorophenol by Trichoderma longibraciatum Isolated from an industrial Soil Sample in Dammam, Saudi Arabia. Sci Rep 2022; 12:2940. [PMID: 35190624 PMCID: PMC8861096 DOI: 10.1038/s41598-022-07016-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 02/09/2022] [Indexed: 12/03/2022] Open
Abstract
2,6-Dichlorophenol (2,6-DCP) is an aromatic compound with industrial importance in making insecticides, herbicides, and other organic compounds. However, it poses serious health and ecological problems. Microbial degradation of 2,6-DCP has been widely applied due to its effectiveness and eco-friendly characteristics. In this study, Trichoderma longibraciatum was isolated from an industrial soil sample in Dammam, Saudi Arabia using the enrichment method of mineral salt's medium (MSM) amended with 2,6-DCP. Morphological and molecular identification (using the internal transcribed spacer rRNA gene sequencing) of the 2,6-DCP tolerating fungal isolate were charactraized. The fungal isolate has demonstrated a tolerance to 2,6-DCP up to 300 mg/L. Mycelial growth and fungal sporulation were reduced with increasing 2,6-DCP concentrations up to 96 h incubation period. However, after 168 h incubation period, the fungal isolate recorded maximum growth at all the tested 2,6-DCP concentrations up to 150 mg/L. Carboxy methyl cellulase production by tested fungus was decreased by increasing 2,6-DCP concentration up to 75 mg/L. The biodegradation pattern of 2,6-DCP in GM liquid medium using GC–mass analysis as well as the degradation pathway was presented. This study provides a promising fungal isolate that could be used in the bioremediation process for chlorinated phenols in soil.
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7
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De Vela RJ, Wigley K, Baronian K, Gostomski PA. Effect of metabolic uncouplers on the performance of toluene-degrading biotrickling filter. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:41881-41895. [PMID: 33791957 DOI: 10.1007/s11356-021-13708-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 03/24/2021] [Indexed: 06/12/2023]
Abstract
The biomass control potential of three metabolic uncouplers (carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP), carbonyl cyanide m-chlorophenylhydrazone (CCCP), and m-chlorophenol (m-CP)) was tested in biotrickling filters (BTFs) degrading toluene. The experiments employed two types of reactors: a traditional column design and a novel differential BTF (DBTF) reactor developed by De Vela and Gostomski (J Environ Eng 147:04020159, 2021). Uncouplers caused the toluene elimination capacity (EC) (~33 g/m3h for column reactors and ~600 g/m3h for DBTF) to decrease by 15-97% in a dose-dependent fashion. The EC completely recovered in the column reactor in 3 to 13 days, while only partial recovery happened in the DBTF. Short-term (1 to 3 days) true uncoupling was indicated by the 20-160% increase in %CO2 recovery, depending on concentration. FCCP and CCCP increased the pressure drop due to increased extracellular polymeric substances (EPS) production for protection against the uncouplers. The 4.0-mM m-CP weakened the biofilm in the BTF bed, as evidenced by the 130-500% increase in the total organic carbon in the liquid sump of the column and DBTF reactors. Moreover, a microbial shift led to the proliferation of genera that degrade uncouplers, further demonstrating that the uncouplers tested were not a sustainable biomass control strategy in BTFs.
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Affiliation(s)
- Roger Jay De Vela
- Chemical and Process Engineering Department, University of Canterbury, Christchurch, New Zealand.
- Camarines Norte State College, F. Pimentel Avenue, 4600, Daet, Camarines Norte, Philippines.
| | - Kathryn Wigley
- Chemical and Process Engineering Department, University of Canterbury, Christchurch, New Zealand
| | - Kim Baronian
- Chemical and Process Engineering Department, University of Canterbury, Christchurch, New Zealand
| | - Peter Alan Gostomski
- Chemical and Process Engineering Department, University of Canterbury, Christchurch, New Zealand
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Yang K, Zhao Y, Ji M, Li Z, Zhai S, Zhou X, Wang Q, Wang C, Liang B. Challenges and opportunities for the biodegradation of chlorophenols: Aerobic, anaerobic and bioelectrochemical processes. WATER RESEARCH 2021; 193:116862. [PMID: 33550168 DOI: 10.1016/j.watres.2021.116862] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 01/17/2021] [Accepted: 01/20/2021] [Indexed: 06/12/2023]
Abstract
Chlorophenols (CPs) are highly toxic and refractory contaminants which widely exist in various environments and cause serious harm to human and environment health and safety. This review provides comprehensive information on typical CPs biodegradation technologies, the most green and benign ones for CPs removal. The known aerobic and anaerobic degradative bacteria, functional enzymes, and metabolic pathways of CPs as well as several improving methods and critical parameters affecting the overall degradation efficiency are systematically summarized and clarified. The challenges for CPs mineralization are also discussed, mainly including the dechlorination of polychlorophenols (poly-CPs) under aerobic condition and the ring-cleavage of monochlorophenols (MCPs) under anaerobic condition. The coupling of functional materials and degraders as well as the operation of sequential anaerobic-aerobic bioreactors and bioelectrochemical system (BES) are promising strategies to overcome some current limitations. Future perspective and research gaps in this field are also proposed, including the further understanding of microbial information and the specific role of materials in CPs biodegradation, the potential application of innovative biotechnologies and new operating modes to optimize and maximize the function of the system, and the scale-up of bioreactors towards the efficient biodegradation of CPs.
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Affiliation(s)
- Kaichao Yang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Yingxin Zhao
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China.
| | - Min Ji
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Zhiling Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Siyuan Zhai
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Xu Zhou
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Qian Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Can Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Bin Liang
- School of Civil & Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China; State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
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9
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Fang L, Qin H, Shi T, Wu X, Li QX, Hua R. Ortho and para oxydehalogenation of dihalophenols catalyzed by the monooxygenase TcpA and NAD(P)H:FAD reductase Fre. JOURNAL OF HAZARDOUS MATERIALS 2020; 388:121787. [PMID: 31818658 DOI: 10.1016/j.jhazmat.2019.121787] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/19/2019] [Accepted: 11/28/2019] [Indexed: 06/10/2023]
Abstract
Dihalophenols such as dichlorophenols (DCPs) are important industrial chemical intermediates, but also persistent pollutants in the environment. Oxidative dehalogenation by microbes is an efficient biological method to degrade halophenols, but the mechanism is unclear yet. Cupriavidus nantongensis X1T was a type strain of genus Cupriavidus, and could degrade 2,4-dichlorophenol of 50 mg/L within 12 h. The degradation rate constant was approximately 84 fold greater than that by Bacillus endophyticus CP1R43, a well-studied 2,4-DCP-degrading bacterial strain. The genes encoding 2,4,6-trichlorophenol monooxygenase (TcpA) and NAD(P)H:FAD reductase (Fre) from strain X1T were cloned and expressed. The expressed TcpA Fre were purified. The molecular docking of TcpA with DCPs and point mutation experiments showed that the degradation activity of TcpA was associated with the length of the hydrogen bond between the substrates and the amino acids in the active pocket. DCPs were degraded via a stepwise oxidative dechlorination in a positive relationship between the oxidation ability and the electron-withdrawing potential of the p-position group. In addition, TcpA has dual dehalogenation and denitration functions. The results demonstrate that either strain X1T or TcpA and Fre can effectively dehalogenate dihalophenols, which can be useful for the treatment of dihalophenols in wastewaters and remediation of DCP-contaminated environments.
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Affiliation(s)
- Liancheng Fang
- Key Laboratory for Agri-Food Safety, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Han Qin
- Key Laboratory for Agri-Food Safety, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Taozhong Shi
- Key Laboratory for Agri-Food Safety, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Xiangwei Wu
- Key Laboratory for Agri-Food Safety, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Qing X Li
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, 1955 East-West Road, Honolulu, HI 96822, United States.
| | - Rimao Hua
- Key Laboratory for Agri-Food Safety, School of Resource & Environment, Anhui Agricultural University, Hefei, Anhui 230036, China.
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10
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Gu J, Chen X, Wang Y, Wang L, Szlavecz K, Ma Y, Ji R. Bioaccumulation, physiological distribution, and biotransformation of tetrabromobisphenol a (TBBPA) in the geophagous earthworm Metaphire guillelmi - hint for detoxification strategy. JOURNAL OF HAZARDOUS MATERIALS 2020; 388:122027. [PMID: 31954300 DOI: 10.1016/j.jhazmat.2020.122027] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 12/23/2019] [Accepted: 01/03/2020] [Indexed: 06/10/2023]
Abstract
The mechanisms underlying the bioaccumulation and detoxification of tetrabromobisphenol A (TBBPA) by terrestrial invertebrates are poorly understood. We used uniformly ring-14C-labelled TBBPA to investigate the bioaccumulation kinetics, metabolites distribution, and subsequent detoxification strategy of TBBPA in the geophagous earthworm Metaphire guillelmi in soil. The modeling of bioaccumulation kinetics showed a higher biota-soil-accumulation-factor of total 14C than that of the parent compound TBBPA, indicating that most of the ingested TBBPA was transformed into metabolites or sequestered as bound residues in the earthworms. Bound-residue formation in the digestive tract may hinder the accumulation of TBBPA in other parts of the body. Nonetheless, via the circulatory system, TBBPA was transferred to other tissues, especially the clitellum region, where sensitive organs are located. In the clitellum region, TBBPA was quickly transformed to less toxic dimethyl TBBPA ether and rapidly depurated through feces. We conclude that the detoxification of TBBPA in M. guillelmi occurred via bound-residue formation in the digestive tract as well as the generation and depuration of O-methylation metabolites. Our results provided direct evidence of TBBPA detoxification in earthworms. Further researches are needed to confirm whether O-methylation coupled with depuration is a common detoxification strategy for phenolic xenobiotics in other soil organisms needs to be determined.
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Affiliation(s)
- Jianqiang Gu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China; Key Laboratory of Environmental Engineering, Jiangsu Academy of Environmental Sciences, 176 Jiangdong Beilu Road, Nanjing, 210036, China
| | - Xian Chen
- School of Chemistry and Environmental Engineering, Jiangsu University of Technology, 1801 Zhongwu Avenue, Changzhou, 213001, China
| | - Yongfeng Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China; Quanzhou Institute for Environmental Protection Industry, Nanjing University, Beifeng Road, Quanzhou, 362000, China
| | - Lianhong Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China
| | - Katalin Szlavecz
- Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Yini Ma
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China.
| | - Rong Ji
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China
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11
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Setlhare B, Kumar A, Mokoena MP, Pillay B, Olaniran AO. Phenol hydroxylase from Pseudomonas sp. KZNSA: Purification, characterization and prediction of three-dimensional structure. Int J Biol Macromol 2020; 146:1000-1008. [PMID: 31726146 DOI: 10.1016/j.ijbiomac.2019.09.224] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 09/13/2019] [Accepted: 09/19/2019] [Indexed: 11/16/2022]
Abstract
A 61.3 kDa Phenol hydroxylase (PheA) was purified and characterized from Pseudomonas sp. KZNSA (PKZNSA). Cell free extract of the isolate grown in mineral salt medium supplemented with 600 ppm phenol showed 21.58 U/mL of PheA activity with a specific activity of 7.67 U/mg of protein. The enzyme was purified to 1.6-fold with a total yield of 33.6%. The purified PheA was optimally active at pH 8 and temperature 30 °C, with ≈95% stability at pH 7.5 and temperature 30 °C after 2 h. The Lineweaver-Burk plot showed the vmax and Km values of 4.04 µM/min and 4.03 µM, respectively, for the substrate phenol. The ES-MS data generated from the tryptic digested fragments of pure protein and PCR amplification of a ≈600 bp gene from genomic DNA of PKZNSA lead to the determination of complete amino acid and nucleotide sequence of PheA. Bioinformatics tools and homology modelling studies indicated that PheA from PKZNSA is likely a probable protein kinase UbiB (2-octaprenylphenol hydroxylase) involving Lys and Asp at positions 153 and 288 for binding and active site, respectively. Characterization and optimization of PheA activity may be useful for a better understanding of 2,4-dichlorophenol degradation by this organism and for potential industrial application of the enzyme.
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Affiliation(s)
- Boitumelo Setlhare
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, South Africa
| | - Ajit Kumar
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, South Africa
| | - Mduduzi P Mokoena
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, South Africa
| | - Bala Pillay
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, South Africa
| | - Ademola O Olaniran
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, South Africa.
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12
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Omics Approaches to Pesticide Biodegradation. Curr Microbiol 2020; 77:545-563. [DOI: 10.1007/s00284-020-01916-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 02/08/2020] [Indexed: 02/08/2023]
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Zhang H, Yu T, Wang Y, Li J, Wang G, Ma Y, Liu Y. 4-Chlorophenol Oxidation Depends on the Activation of an AraC-Type Transcriptional Regulator, CphR, in Rhodococcus sp. Strain YH-5B. Front Microbiol 2018; 9:2481. [PMID: 30405555 PMCID: PMC6205950 DOI: 10.3389/fmicb.2018.02481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 09/28/2018] [Indexed: 11/13/2022] Open
Abstract
4-Chlorophenol (4-CP) oxidation plays an essential role in the detoxification of 4-CP. However, oxidative regulation of 4-CP at the genetic and biochemical levels has not yet been studied. To explore the regulation mechanism of 4-CP oxidation, a novel gene cluster, cphRA2A1, involved in biodegradation of 4-CP was identified and cloned from Rhodococcus sp. strain YH-5B by genome walking. The sequence analysis showed that the cphRA2A1 gene cluster encoded an AraC-type transcriptional regulator and a two-component monooxygenase enzyme, while quantitative real-time PCR analysis further revealed that cphR was constitutively expressed and positively regulated the transcription of cphA2A1 genes in response to 4-CP or phenol, as evidenced by gene knockout and complementation experiments. Through the transcriptional fusion of the mutated cphA2A1 promoter with the lacZ gene, it was found that the CphR regulator binding sites had two 15-bp imperfect direct repeats (TGCA-N6-GGNTA) at -35 to -69 upstream of the cphA2A1 transcriptional start site. Notably, the sub-motifs at the -46 to -49 positions played a critical role in the appropriate interaction with the CphR dimer. In addition, it was confirmed that the monooxygenase subunits CphA1 and CphA2, which were purified by His-tag affinity chromatography, were able to catalyze the conversion of 4-CP to 4-chlorocatechol, suggesting that strain YH-5B could degrade 4-CP via the 4-chlorocatechol pathway. This study enhances our understanding of the genetic and biochemical diversity in the transcriptional regulation of 4-CP oxidation in Gram-positive bacteria.
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Affiliation(s)
- Hui Zhang
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Ting Yu
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Yiran Wang
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Jie Li
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Guangli Wang
- College of Life Sciences, Huaibei Normal University, Huaibei, China
- Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, Singapore, Singapore
| | - Yingqun Ma
- Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, Singapore, Singapore
| | - Yu Liu
- Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, Singapore, Singapore
- School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, Singapore
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14
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Bacterial Biodegradation of 4-Monohalogenated Diphenyl Ethers in One-Substrate and Co-Metabolic Systems. Catalysts 2018. [DOI: 10.3390/catal8100472] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The use of diphenyl ether (DE) and its 4-monohalogenated derivatives (4-HDE) as flame retardants, solvents, and substrates in biocide production significantly increases the risk of ecosystem contamination. Their removal is important from the point of view of environmental protection. The aim of this study was to evaluate the degradation processes of DE and 4-HDE by enzymes of the environmental bacterial strains under one-substrate and co-metabolic conditions. The study is focused on the biodegradation of DE and 4-HDE, the enzymatic activity of microbial strains, and the cell surface properties after contact with compounds. The results show that the highest biodegradation (96%) was observed for 4-chlorodiphenyl ether in co-metabolic culture with P. fluorescens B01. Moreover, the activity of 1,2-dioxygenase during degradation of 4-monohalogenated diphenyl ethers was higher than that of 2,3-dioxygenase for each strain tested. The presence of a co-substrate provoked changes in dioxygenase activity, resulting in the increased activity of 1,2-dioxygenase. Moreover, the addition of phenol as a co-substrate allowed for increased biodegradation of the diphenyl ethers and noticeable modification of the cell surface hydrophobicity during the process. All observations within the study performed have led to a deeper understanding of the contaminants’ biodegradation processes catalyzed by environmental bacteria.
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Kwean OS, Cho SY, Yang JW, Cho W, Park S, Lim Y, Shin MC, Kim HS, Park J, Kim HS. 4-Chlorophenol biodegradation facilitator composed of recombinant multi-biocatalysts immobilized onto montmorillonite. BIORESOURCE TECHNOLOGY 2018; 259:268-275. [PMID: 29571170 DOI: 10.1016/j.biortech.2018.03.066] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/11/2018] [Accepted: 03/12/2018] [Indexed: 06/08/2023]
Abstract
A biodegradation facilitator which catalyzes the initial steps of 4-chlorophenol (4-CP) oxidation was prepared by immobilizing multiple enzymes (monooxygenase, CphC-I and dioxygenase, CphA-I) onto a natural inorganic support. The enzymes were obtained via overexpression and purification after cloning the corresponding genes (cphC-I and cphA-I) from Arthrobacter chlorophenolicus A6. Then, the recombinant CphC-I was immobilized onto fulvic acid-activated montmorillonite. The immobilization yield was 60%, and the high enzyme activity (82.6%) was retained after immobilization. Kinetic analysis indicated that the Michaelis-Menten model parameters for the immobilized CphC-I were similar to those for the free enzyme. The enzyme stability was markedly enhanced after immobilization. The immobilized enzyme exhibited a high level of activity even after repetitive use (84.7%) and powdering (65.8%). 4-CP was sequentially oxidized by a multiple enzyme complex, comprising the immobilized CphC-I and CphA-I, via the hydroquinone pathway: oxidative transformation of 4-CP to hydroxyquinol followed by ring fission of hydroxyquinol.
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Affiliation(s)
- Oh Sung Kwean
- Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05030, Republic of Korea
| | - Su Yeon Cho
- Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05030, Republic of Korea
| | - Jun Won Yang
- Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05030, Republic of Korea
| | - Wooyoun Cho
- Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05030, Republic of Korea
| | - Sungyoon Park
- Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05030, Republic of Korea
| | - Yejee Lim
- Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05030, Republic of Korea
| | - Min Chul Shin
- Environmental Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju Jeollabuk-do 54896, Republic of Korea; The Soil and R&D Center, H-Plus Eco Ltd., 222 Seokchonhosu-ro, Songpa-gu, Seoul 05610, Republic of Korea
| | - Han-Suk Kim
- The Soil and R&D Center, H-Plus Eco Ltd., 222 Seokchonhosu-ro, Songpa-gu, Seoul 05610, Republic of Korea
| | - Joonhong Park
- Civil and Environmental Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Han S Kim
- Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05030, Republic of Korea.
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16
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Zhang C, Fu L, Xu Z, Xiong H, Zhou D, Huo M. Contrasting roles of phenol and pyrocatechol on the degradation of 4-chlorophenol in a photocatalytic–biological reactor. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:24725-24731. [PMID: 28942472 DOI: 10.1007/s11356-017-0245-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 09/19/2017] [Indexed: 05/24/2023]
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17
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Patel BP, Kumar A. Multi-substrate biodegradation of chlorophenols by defined microbial consortium. 3 Biotech 2016; 6:191. [PMID: 28330263 PMCID: PMC5010539 DOI: 10.1007/s13205-016-0511-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 08/28/2016] [Indexed: 11/28/2022] Open
Abstract
In the present study, a defined mixed microbial consortium was investigated for their ability to utilize three different monochlorophenols (MCPs) and 2,4-DCP individually and in the mixture. None of the individual strains were able to utilize 3-CP and 4-CP, but when they were mixed to form defined consortium, they have shown great potential and degradation of high concentration of 3-CP and 4-CP. Spectrophotometric analysis of metabolites during MCPs degradation establishes the presence of 2-chloromaleylacetate. Multi-substrate degradation study of 2,4-DCP in the presence of three MCPs showed the great prospect of microbial consortium for in situ bioremediation. During multi-substrate degradation, the biodegradation rate (mg L-1 day-1) was observed in the order of 2,4-DCP > 2CP > 3CP > 4CP. Biodegradation kinetic of three MCPs using Andrew's model showed maximum removal rate (R m) of 2.78, 0.91, 1.82 mg L-1 h-1 for 2-CP, 3-CP and 4-CP, respectively.
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Affiliation(s)
- Bhishma P. Patel
- Value Addition, Research and Development Department, National Innovation Foundation-India, Satellite Complex, Jodhpur Tekra, Ahmedabad, 380015 Gujarat India
| | - Arvind Kumar
- Environmental Pollution Abatement Lab, Chemical Engineering Department, National Institute of Technology, Rourkela, 769008 Odisha India
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19
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Li Y, Zhang R, Du L, Zhang Q, Wang W. Insights into the catalytic mechanism of chlorophenol 4-monooxygenase: a quantum mechanics/molecular mechanics study. RSC Adv 2015. [DOI: 10.1039/c4ra16165c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The degradation mechanism of chlorophenol 4-monooxygenase toward pollutants 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, and 2,5-dichloro-p-hydroquinone was studied by QM/MM investigations.
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Affiliation(s)
- Yanwei Li
- Environment Research Institute
- Shandong University
- Jinan 250100, P. R. China
| | - Ruiming Zhang
- Environment Research Institute
- Shandong University
- Jinan 250100, P. R. China
| | - Likai Du
- Key Laboratory of Bio-based Materials
- Qingdao Institute of Bio-energy and Bioprocess Technology
- Chinese Academy of Sciences
- Qingdao 266101, P. R. China
| | - Qingzhu Zhang
- Environment Research Institute
- Shandong University
- Jinan 250100, P. R. China
| | - Wenxing Wang
- Environment Research Institute
- Shandong University
- Jinan 250100, P. R. China
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20
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Arora PK, Bae H. Bacterial degradation of chlorophenols and their derivatives. Microb Cell Fact 2014; 13:31. [PMID: 24589366 PMCID: PMC3975901 DOI: 10.1186/1475-2859-13-31] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 02/20/2014] [Indexed: 12/02/2022] Open
Abstract
Chlorophenols (CPs) and their derivatives are persistent environmental pollutants which are used in the manufacture of dyes, drugs, pesticides and other industrial products. CPs, which include monochlorophenols, polychlorophenols, chloronitrophenols, chloroaminophenols and chloromethylphenols, are highly toxic to living beings due to their carcinogenic, mutagenic and cytotoxic properties. Several physico-chemical and biological methods have been used for removal of CPs from the environment. Bacterial degradation has been considered a cost-effective and eco-friendly method of removing CPs from the environment. Several bacteria that use CPs as their sole carbon and energy sources have been isolated and characterized. Additionally, the metabolic pathways for degradation of CPs have been studied in bacteria and the genes and enzymes involved in the degradation of various CPs have been identified and characterized. This review describes the biochemical and genetic basis of the degradation of CPs and their derivatives.
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Affiliation(s)
- Pankaj Kumar Arora
- School of Biotechnology, Yeungnam University, Gyeongsan 712-749, Republic of Korea
| | - Hanhong Bae
- School of Biotechnology, Yeungnam University, Gyeongsan 712-749, Republic of Korea
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21
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Micalella C, Caglio R, Mozzarelli A, Valetti F, Pessione E, Giunta C, Bruno S. Ormosil gels doped with engineered catechol 1,2 dioxygenases for chlorocatechol bioremediation. Biotechnol Appl Biochem 2014; 61:297-303. [PMID: 24571591 DOI: 10.1002/bab.1162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 10/01/2013] [Indexed: 11/06/2022]
Abstract
Enzymes entrapped in wet, nanoporous silica gel have great potential as bioreactors for bioremediation because of their improved thermal, chemical, and mechanical stability with respect to enzymes in solution. The B isozyme of catechol 1,2 dioxygenase from Acinetobacter radioresistens and its mutants of Leu69 and Ala72, designed for an increased reactivity toward the environmental pollutant chlorocatechols, were encapsulated using alkoxysilanes and alkyl alkoxysilanes as precursors in varying proportions. Encapsulation of the mutants in a hydrophobic tetramethoxysilane/dimethoxydimethylsilane-based matrix yielded a remarkable 10- to 12-fold enhancement in reactivity toward chlorocatechols. These gels also showed a fivefold increase in relative reactivity toward chlorocatechols with respect to the natural substrate catechol, thus compensating for their relatively low activity for these substrates in solution. The encapsulated enzyme, unlike the enzyme in solution, proved resilient in assays carried out in urban wastewater and bacteria-contaminated solutions mimicking environmentally relevant conditions. Overall, the combination of a structure-based rational design of enzyme mutants, and the selection of a suitable encapsulation material, proved to be a powerful approach for the production and optimization of a potential bioremediation device, with increased activity and resistance toward bacterial degradation.
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22
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Karn SK. Pentachlorophenol remediation by Enterobacter sp. SG1 isolated from industrial dump site. Pak J Biol Sci 2014; 17:388-94. [PMID: 24897793 DOI: 10.3923/pjbs.2014.388.394] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Chlorophenols contamination is serious concern to the environment due toxicity to all forms of life. Among all the chlorophenols, pentachlorophenol (PCP) is more detrimental to the environment. Pentachlorophenol used as pesticide, herbicide, antifungal agent and wood preservative which causes environmental pollution. In the present research a PCP degrading bacterium was isolated and characterized from industrial dump site. This isolate used PCP as its sole source of carbon and energy and was capable of degrading this compound, as indicated by stoichiometric release of chloride, ring cleavage activity and biomass formation. Based on morphological, biochemical and 16S rRNA gene sequence analysis this strain was identified as Enterobacter sp. SG1. Gas Chromatography (GC) analysis revealed that this strain was able to degrade PCP up to a concentration of 2 mM. This study showed that the removal efficiency of PCP by SG1 was found to be very effective and can be used in degradation of PCP contaminated site or waste in the environment.
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23
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Sinkkonen A, Ollila S, Romantschuk M. Changes in TcpA gene frequency explain 2,4,6-trichlorophenol degradation in mesocosms. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART. B, PESTICIDES, FOOD CONTAMINANTS, AND AGRICULTURAL WASTES 2014; 49:756-759. [PMID: 25065827 DOI: 10.1080/03601234.2014.929865] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Soils are often polluted by chlorophenols in timber production areas in the northern hemisphere. The tcpA gene encodes the first step of 2,4,6-trichlorophenol (246-TCP) degradation. We tested tcpA gene frequency in three natural pristine soils with different 246-TCP degradation capacity. Gene tcpA frequency increased more in spiked than non-spiked 10-L pails containing coniferous humus soil with high degradation capacity, in contrast to soils where degradation was slower. As the soil in each mesocosm originated from a spatially separate field plot, changes in tcpA gene frequency affected 246-TCP degradation over a range of soil origins. This indicates that the abundance of and changes in tcpA gene frequency could be utilized in estimating the efficacy of natural attenuation and biostimulation treatments in controlled conditions.
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Affiliation(s)
- Aki Sinkkonen
- a University of Helsinki , Department of Environmental Sciences , Lahti , Finland
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24
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Tarnow P, Tralau T, Hunecke D, Luch A. Effects of triclocarban on the transcription of estrogen, androgen and aryl hydrocarbon receptor responsive genes in human breast cancer cells. Toxicol In Vitro 2013; 27:1467-75. [PMID: 23524099 DOI: 10.1016/j.tiv.2013.03.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 03/04/2013] [Accepted: 03/12/2013] [Indexed: 12/20/2022]
Abstract
Triclocarban (TCC) is an antimicrobial agent that is used in detergents, soaps and other personal hygiene products. Similarly to triclosan the widespread use of TCC has raised concerns about its endocrine potential. In luciferase-based reporter assays TCC has been shown to enhance estrogenic and androgenic activities following cellular coexposure with estrogen or dihydrotestosterone, respectively. The present study demonstrates that although coexposure with TCC enhances the estrogenic and androgenic readout of luciferase-based reporter cell lines such as HeLa9908 and MDA-kb2, it fails to act as a xenoandrogen on transcriptional level, nor does it induce cell proliferation in the estrogen sensitive E-screen. In addition TCC did not alter the expression of estrogen responsive genes in human mammary carcinoma MCF-7 cells exposed to 17β-estradiol, bisphenol A, butylparaben or genistein. However, TCC was shown to interfere with the regulon of the aryl hydrocarbon receptor (AhR) as TCC showed a costimulatory effect on transcription of CYP1A1 and CYP1B1, effectively lowering the transcriptional threshold for both genes in the presence of estrogens. It thus seems, that while the induction of the respective luciferase reporter assays by TCC is an unspecific false positive signal caused by luciferase stabilisation, TCC has the potential to interfere with the regulatory crosstalk of the estrogen receptor (ER) and the AhR regulon.
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Affiliation(s)
- Patrick Tarnow
- German Federal Institute for Risk Assessment (BfR), Department of Product Safety, Berlin, Germany.
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25
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Nikel PI, Pérez-Pantoja D, de Lorenzo V. Why are chlorinated pollutants so difficult to degrade aerobically? Redox stress limits 1,3-dichloroprop-1-ene metabolism by Pseudomonas pavonaceae. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120377. [PMID: 23479756 DOI: 10.1098/rstb.2012.0377] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Chlorinated pollutants are hardly biodegradable under oxic conditions, but they can often be metabolized by anaerobic bacteria through organohalide respiration reactions. In an attempt to identify bottlenecks limiting aerobic catabolism of 1,3-dichloroprop-1-ene (1,3-DCP; a widely used organohalide) in Pseudomonas pavonaceae, the possible physiological restrictions for this process were surveyed. Flow cytometry and a bioluminescence reporter of metabolic state revealed that cells treated with 1,3-DCP experienced an intense stress that could be traced to the endogenous production of reactive oxygen species (ROS) during the metabolism of the compound. Cells exposed to 1,3-DCP also manifested increased levels of D-glucose-6-P 1-dehydrogenase activity (G6PDH, an enzyme key to the synthesis of reduced NADPH), observed under both glycolytic and gluconeogenic growth regimes. The increase in G6PDH activity, as well as cellular hydroperoxide levels, correlated with the generation of ROS. Additionally, the high G6PDH activity was paralleled by the accumulation of D-glucose-6-P, suggesting a metabolic flux shift that favours the production of NADPH. Thus, G6PDH and its cognate substrate seem to play an important role in P. pavonaceae under redox stress caused by 1,3-DCP, probably by increasing the rate of NADPH turnover. The data suggest that oxidative stress associated with the biodegradation of 1,3-DCP reflects a significant barrier for the evolution of aerobic pathways for chlorinated compounds, thereby allowing for the emergence of anaerobic counterparts.
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Affiliation(s)
- Pablo I Nikel
- Systems and Synthetic Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Madrid 28049, Spain
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26
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Karn SK, Reddy MS. Removal of 2,4,5-trichlorophenol by bacterial isolates from the secondary sludge of pulp and paper mill. J Basic Microbiol 2012; 53:752-7. [PMID: 22961799 DOI: 10.1002/jobm.201200163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Accepted: 06/01/2012] [Indexed: 11/11/2022]
Abstract
2,4,5-trichlorophenol (2,4,5-TCP) mineralizing bacteria were isolated from the secondary sludge of pulp and paper industry. These isolates used 2,4,5-TCP as a source of carbon and energy and were capable of degrading this compound, as indicated by stoichimetric release of chloride and biomass formation. Based on 16S rRNA sequence analysis, these bacteria were identified as Kocuria sp. (CL2), Bacillus pumillus (CL5), Pseudomonas stutzeri (CL7). HPLC analysis revealed that these isolates were able to degrade 2,4,5-TCP at higher concentrations (600 mg/l or 3.0 mM). A consortia of these isolates completely removed 2,4,5-TCP from the sludge obtained from pulp and paper mill within 2 weeks when supplemented at a rate of 100 mg l(-1) . Bacterial consortium also significantly reduced absorbable organic halogen (AOX) and extractable organic halogen (EOX) by 61% and 63%, respectively from the sludge. These isolates have high potential to remove 2,4,5-TCP and may be used for remediation of pulp paper mill waste containing 2,4,5-TCP.
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Affiliation(s)
- Santosh Kr Karn
- Department of Biotechnology, Thapar University, Patiala, 147 004, Punjab, India
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Induction of DNA double-strand breaks by monochlorophenol isomers and ChKM in human gingival fibroblasts. Arch Toxicol 2012; 86:1423-9. [PMID: 22614568 DOI: 10.1007/s00204-012-0861-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 11/16/2011] [Indexed: 10/28/2022]
Abstract
Phenol has been traditionally used in dental treatment as a sedative for the pulp or as disinfectant for carious cavity and root canal. However, phenol is regarded as a mutagenic and carcinogenic agent and its use in dental practice is now therefore restricted. Monochlorophenols are derivatives of phenol, which are still used clinically as root canal disinfectants, they are even more active antiseptics/disinfectants than phenol, and the so-called Walkhoff (ChKM) solution makes use of monochlorophenol for root canal disinfection. Ingredients in the ChKM solution are the monochlorophenol compound 4-chlorophenol (4-CP), camphor, and menthol. In literature, the use of the ChKM solution is controversial because of a possible DNA toxicity of the ingredient 4-CP. However, it is unknown whether ChKM can really induce DNA damage in human oral cells. In this study, the induction of DNA double-strand breaks (DSBs) by ChKM and monochlorophenol compounds (2-chlorophenol, 2-CP; 3-chlorophenol, 3-CP; and 4-chlorophenol, 4-CP) was tested in human gingival fibroblasts (HGFs). DNA DSBs (foci) induced in HGFs unexposed and exposed to monochlorophenols or ChKM solution were investigated using the γ-H2AX DNA focus assay, which is a direct marker for DSBs. DSBs result in the ATM-dependent phosphorylation of the histone H2AX. When cells were exposed to medium or medium + DMSO (1 %) (negative controls), an average of 3 foci per cell were found. In positive control cells (H₂O₂ + medium, or H₂O₂ + medium + DMSO (1 %), an average of 35 foci each were found. About 20 DSB foci per cell were found, when HGFs were exposed to 2-CP (4 mM), 3-CP (2.3 mM), 4-CP (2.1 mM), or ChKM (corresponding to 1.5 mM 4-CP). Our results show increasing DNA toxicities in the order of 2-CP < 3-CP < 4-CP < ChKM solution. An additive DNA toxicity was found for 4-CP in combination with camphor in the ChKM solution, compared to the 4-CP alone. No significant differences regarding multi-foci cells (cells that contain more than 40 foci) were found when HGFs were exposed to the EC₅₀ concentrations (given in parenthesis) of ChKM (1.5 mM), 4-CP (2.1 mM), or 2-CP (4 mM). Significantly fewer multi-foci cells were found when HGFs were exposed to the EC₅₀ concentration (given in parenthesis) of 3-CP (2.3 mM), compared to the EC₅₀ concentrations of ChKM, 4-CP, or 2-CP. Monochlorophenol compounds and/or ChKM solution can induce DSBs in primary human oral (cavity) cells, which underscores their genotoxic capacity.
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del Castillo I, Hernández P, Lafuente A, Rodríguez-Llorente ID, Caviedes MA, Pajuelo E. Self-bioremediation of cork-processing wastewaters by (chloro)phenol-degrading bacteria immobilised onto residual cork particles. WATER RESEARCH 2012; 46:1723-1734. [PMID: 22265252 DOI: 10.1016/j.watres.2011.12.038] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 12/16/2011] [Accepted: 12/18/2011] [Indexed: 05/31/2023]
Abstract
Cork manufacturing is a traditional industry in Southern Europe, being the main application of this natural product in wine stoppers and insulation. Cork processing begins at boiling the raw material. As a consequence, great volumes of dark wastewaters, with elevated concentrations of chlorophenols, are generated, which must be depurated through costly physicochemical procedures before discarding them into public water courses. This work explores the potential of bacteria, isolated from cork-boiling waters storage ponds, in bioremediation of the same effluent. The bacterial population present in cork-processing wastewaters was analysed by DGGE; low bacterial biodiversity was found. Aerobic bacteria were isolated and investigated for their tolerance against phenol and two chlorophenols. The most tolerant strains were identified by sequencing 16S rDNA. The phenol-degrading capacity was investigated by determining enzyme activities of the phenol-degrading pathway. Moreover, the capacity to form biofilms was analysed in a microtitre plate assay. Finally, the capacity to form biofilms onto the surface of residual small cork particles was evaluated by acridine staining followed by epifluorescence microscopy and by SEM. A low-cost bioremediation system, using phenol-degrading bacteria immobilised onto residual cork particles (a by-product of the industry) is proposed for the remediation of this industrial effluent (self-bioremediation).
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Affiliation(s)
- I del Castillo
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/Profesor García González, 2, 41012 Sevilla, Spain
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Karn SK, Reddy MS. Degradation of 2,4,6-trichlorophenol by bacteria isolated from secondary sludge of a pulp and paper mill. J GEN APPL MICROBIOL 2012; 58:413-20. [DOI: 10.2323/jgam.58.413] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Recio E, Alvarez-Rodríguez ML, Rumbero A, Garzón E, Coque JJR. Destruction of chloroanisoles by using a hydrogen peroxide activated method and its application to remove chloroanisoles from cork stoppers. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:12589-12597. [PMID: 22074456 DOI: 10.1021/jf2035753] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A chemical method for the efficient destruction of 2,4,6-trichloroanisole (TCA) and pentachloroanisole (PCA) in aqueous solutions by using hydrogen peroxide as an oxidant catalyzed by molybdate ions in alkaline conditions was developed. Under optimal conditions, more than 80.0% TCA and 75.8% PCA were degraded within the first 60 min of reaction. Chloroanisoles destruction was followed by a concomitant release of up to 2.9 chloride ions per TCA molecule and 4.6 chloride ions per PCA molecule, indicating an almost complete dehalogenation of chloroanisoles. This method was modified to be adapted to chloroanisoles removal from the surface of cork materials including natural cork stoppers (86.0% decrease in releasable TCA content), agglomerated corks (78.2%), and granulated cork (51.3%). This method has proved to be efficient and inexpensive with practical application in the cork industry to lower TCA levels in cork materials.
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Affiliation(s)
- Eliseo Recio
- Instituto de Biotecnología de León (INBIOTEC), 24006-León, Spain
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Solyanikova I, Golovleva L. Biochemical features of the degradation of pollutants by Rhodococcus as a basis for contaminated wastewater and soil cleanup. Microbiology (Reading) 2011. [DOI: 10.1134/s0026261711050158] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Olaniran AO, Igbinosa EO. Chlorophenols and other related derivatives of environmental concern: properties, distribution and microbial degradation processes. CHEMOSPHERE 2011; 83:1297-306. [PMID: 21531434 DOI: 10.1016/j.chemosphere.2011.04.009] [Citation(s) in RCA: 246] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 04/01/2011] [Accepted: 04/04/2011] [Indexed: 05/24/2023]
Abstract
Chlorophenols are chlorinated aromatic compound structures and are commonly found in pesticide preparations as well as industrial wastes. They are recalcitrant to biodegradation and consequently persistent in the environment. A variety of chlorophenols derivatives compounds are highly toxic, mutagenic and carcinogenic for living organisms. Biological transformation by microorganisms is one of the key remediation options that can be exploited to solve environmental pollution problems caused by these notorious compounds. The key enzymes in the microbial degradation of chlorophenols are the oxygenases and dioxygenases. These enzymes can be engineered for enhanced degradation of highly chlorinated aromatic compounds through directed evolution methods. This review underscores the mechanisms of chlorophenols biodegradation with the view to understanding how bioremediation processes can be optimized for cleaning up chloroaromatic contaminated environments.
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Affiliation(s)
- Ademola O Olaniran
- Discipline of Microbiology, School of Biochemistry, Genetics and Microbiology, Faculty of Science and Agriculture, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, South Africa.
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Karn SK, Chakrabarti SK, Reddy MS. Degradation of pentachlorophenol by Kocuria sp. CL2 isolated from secondary sludge of pulp and paper mill. Biodegradation 2010; 22:63-9. [DOI: 10.1007/s10532-010-9376-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Accepted: 05/25/2010] [Indexed: 11/28/2022]
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Biodegradation: gaining insight through proteomics. Biodegradation 2010; 21:861-79. [DOI: 10.1007/s10532-010-9361-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Accepted: 04/13/2010] [Indexed: 10/19/2022]
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Carvalho MB, Martins I, Leitão MC, Garcia H, Rodrigues C, San Romão V, McLellan I, Hursthouse A, Silva Pereira C. Screening pentachlorophenol degradation ability by environmental fungal strains belonging to the phyla Ascomycota and Zygomycota. J Ind Microbiol Biotechnol 2009; 36:1249-56. [PMID: 19543759 DOI: 10.1007/s10295-009-0603-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Accepted: 05/27/2009] [Indexed: 11/28/2022]
Affiliation(s)
- Mariana B Carvalho
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal
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Pandey J, Chauhan A, Jain RK. Integrative approaches for assessing the ecological sustainability ofin situbioremediation. FEMS Microbiol Rev 2009; 33:324-75. [PMID: 19178567 DOI: 10.1111/j.1574-6976.2008.00133.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Emanuelsson MAE, Osuna MB, Sipma J, Castro PML. Treatment of halogenated organic compounds and monitoring of microbial dynamics in up-flow fixed bed reactors under sequentially alternating pollutant scenarios. Biotechnol Bioeng 2008; 99:800-10. [PMID: 17722081 DOI: 10.1002/bit.21630] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Two up-flow fixed bed reactors (UFBR) were operated for 8 months treating a model synthetic wastewater containing 2-fluorobenzoate (2-FB) and dichloromethane (DCM). The stability of the reactors under dynamic conditions, that is, sequentially alternating pollutants (SAP), shock loads, and starvation periods was assessed. Two support materials were used: expanded clay (EC) that does not adsorb 2-FB or DCM, and granular-activated carbon (GAC) that adsorbs 180 mg g(-1) of 2-FB and 390 mg g(-1) of DCM. The reactors were inoculated with a 2-FB-degrading strain (FB2) and a DCM degrader (TM1). 2-FB was fed at organic loads ranging from 0 to 800 mg L(-1) d(-1), while DCM was fed at 0-250 mg L(-1) d(-1). 2-FB or DCM were never detected at the outlet of the GAC reactor, while in the EC reactor outlet small amounts were observed. Nevertheless, the highest biological elimination capacity was observed in the EC reactor (over 700 mg L(-1) d(-1) of 2-FB). DGGE analysis revealed a fairly stable bacterial community with the largest shifts occurring during starvation periods and changes in feed composition. Several bacterial strains isolated from the reactors showed capacity for 2-FB degradation, while only strain TM1 degraded DCM.
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Affiliation(s)
- Maria A E Emanuelsson
- Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal
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Goswami M, Recio E, Campoy S, Martín JF, Coque JJR. Environmental significance of O-demethylation of chloroanisoles by soil bacterial isolates as a mechanism that improves the overall biodegradation of chlorophenols. Environ Microbiol 2007; 9:2512-21. [PMID: 17803776 DOI: 10.1111/j.1462-2920.2007.01370.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biodegradation rate of chlorophenols in the environment seems to be limited by a competitive mechanism of O-methylation which produces chloroanisoles with a high potential of being bioconcentrated in living organisms. In this work we report for the first time the isolation of three soil bacterial strains able to efficiently degrade 2,4,6-trichloroanisole (2,4,6-TCA). These strains were identified as Xanthomonas retroflexus INBB4, Pseudomonas putida INBP1 and Acinetobacter radioresistens INBS1. In these isolates 2,4,6-TCA was efficiently metabolized in a minimal medium containing methanol and 2,4,6-TCA as the only carbon sources, with a concomitant release of 3 mol of chloride ion from 1 mol of 2,4,6-TCA, indicating complete dehalogenation of 2,4,6-TCA. 2,4,6-trichlorophenol (2,4,6-TCP) was identified as a degradative intermediate, indicating that 2,4,6-TCA underwent O-demethylation as the first step in the biodegradation process. 2,4,6-TCP was further transformed into 2,6-dichloro-para-hydroquinone (2,6-DCHQ) and subsequently mineralized. The degradation of chloroanisoles could improve the overall biodegradation of chlorophenols in the environment, because those chlorophenols previously biomethylated might also be later biodegraded. Xanthomonas retroflexus INBB4 has two O-demethylation systems: one is an oxygenase-type demethylase, and the other is a tetrahydrofolate (THF)-dependent O-demethylase. On the contrary O-demethylation of 2,4,6-TCA in P. putida INBP1 is just catalysed by an oxygenase-type NADH/NADPH-dependent O-demethylase, whereas in A. radioresistens INBS1 a THF-dependent O-demethylase activity was detected.
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Affiliation(s)
- Mandira Goswami
- Instituto de Biotecnología INBIOTEC, Parque Científico de León, Avenida Real, 24006, León, Spain
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Ferraroni M, Kolomytseva MP, Solyanikova IP, Scozzafava A, Golovleva LA, Briganti F. Crystal structure of 3-chlorocatechol 1,2-dioxygenase key enzyme of a new modified ortho-pathway from the Gram-positive Rhodococcus opacus 1CP grown on 2-chlorophenol. J Mol Biol 2006; 360:788-99. [PMID: 16793061 DOI: 10.1016/j.jmb.2006.05.046] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Revised: 05/15/2006] [Accepted: 05/18/2006] [Indexed: 11/18/2022]
Abstract
The crystal structure of the 3-chlorocatechol 1,2-dioxygenase from the Gram-positive bacterium Rhodococcus opacus (erythropolis) 1CP, a Fe(III) ion-containing enzyme specialized in the aerobic biodegradation of 3-chloro- and methyl-substituted catechols, has been solved by molecular replacement techniques using the coordinates of 4-chlorocatechol 1,2-dioxygenase from the same organism (PDB code 1S9A) as a starting model and refined at 1.9 A resolution (R(free) 21.9%; R-factor 17.4%). The analysis of the structure and of the kinetic parameters for a series of different substrates, and the comparison with the corresponding data for the 4-chlorocatechol 1,2-dioxygenase isolated from the same bacterial strain, provides evidence of which active site residues are responsible for the observed differences in substrate specificity. Among the amino acid residues expected to interact with substrates, only three are altered Val53(Ala53), Tyr78(Phe78) and Ala221(Cys224) (3-chlorocatechol 1,2-dioxygenase(4-chlorocatechol 1,2-dioxygenase)), clearly identifying the substitutions influencing substrate selectivity in these enzymes. The crystallographic asymmetric unit contains eight subunits (corresponding to four dimers) that show heterogeneity in the conformation of a co-crystallized molecule bound to the catalytic non-heme iron(III) ion resembling a benzohydroxamate moiety, probably a result of the breakdown of recently discovered siderophores synthesized by Gram-positive bacteria. Several different modes of binding benzohydroxamate into the active site induce distinct conformations of the interacting protein ligands Tyr167 and Arg188, illustrating the plasticity of the active site origin of the more promiscuous substrate preferences of the present enzyme.
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Affiliation(s)
- Marta Ferraroni
- Dipartimento di Chimica, Università di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino (FI), Italy
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