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Fulk EM, Gao X, Lu LC, Redeker KR, Masiello CA, Silberg JJ. Nondestructive Chemical Sensing within Bulk Soil Using 1000 Biosensors Per Gram of Matrix. ACS Synth Biol 2022; 11:2372-2383. [PMID: 35715210 DOI: 10.1021/acssynbio.2c00083] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gene expression can be monitored in hard-to-image environmental materials using gas-reporting biosensors, but these outputs have only been applied in autoclaved matrices that are hydrated with rich medium. To better understand the compatibility of indicator gas reporting with environmental samples, we evaluated how matrix hydration affects the gas signal of an engineered microbe added to a sieved soil. A gas-reporting microbe presented a gas signal in a forest soil (Alfisol) when hydrated to an environmentally relevant osmotic pressure. When the gas signal was concentrated prior to analysis, a biosensor titer of 103 cells/gram of soil produced a significant signal when soil was supplemented with halides. A signal was also observed without halide amendment, but a higher cell titer (106 cells/gram of soil) was required. A sugar-regulated gas biosensor was able to report with a similar level of sensitivity when added to an unsterilized soil matrix, illustrating how gas concentration enables biosensing within a soil containing environmental microbes. These results establish conditions where engineered microbes can report on gene expression in living environmental matrices with decreased perturbation of the soil environment compared to previously reported approaches, using biosensor titers that are orders of magnitude lower than the number of cells typically observed in a gram of soil.
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Affiliation(s)
- Emily M Fulk
- Systems, Synthetic, and Physical Biology Graduate Program, Rice University, 6100 Main Street, MS-180, Houston, Texas 77005, United States
| | - Xiaodong Gao
- Department of Earth, Environmental and Planetary Sciences, Rice University, 6100 Main St, MS-126, Houston, Texas 77005, United States
| | - Li Chieh Lu
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Kelly R Redeker
- Department of Biology, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Caroline A Masiello
- Department of Earth, Environmental and Planetary Sciences, Rice University, 6100 Main St, MS-126, Houston, Texas 77005, United States.,Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States.,Department of Chemistry, Rice University, 6100 Main Street, MS-60, Houston, Texas 77005, United States
| | - Jonathan J Silberg
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States.,Department of Bioengineering, Rice University, 6100 Main Street, MS-142, Houston, Texas 77005, United States.,Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, MS-362, Houston, Texas 77005, United States
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Kröber E, Kanukollu S, Wende S, Bringel F, Kolb S. A putatively new family of alphaproteobacterial chloromethane degraders from a deciduous forest soil revealed by stable isotope probing and metagenomics. ENVIRONMENTAL MICROBIOME 2022; 17:24. [PMID: 35527282 PMCID: PMC9080209 DOI: 10.1186/s40793-022-00416-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 04/19/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Chloromethane (CH3Cl) is the most abundant halogenated organic compound in the atmosphere and substantially responsible for the destruction of the stratospheric ozone layer. Since anthropogenic CH3Cl sources have become negligible with the application of the Montreal Protocol (1987), natural sources, such as vegetation and soils, have increased proportionally in the global budget. CH3Cl-degrading methylotrophs occurring in soils might be an important and overlooked sink. RESULTS AND CONCLUSIONS The objective of our study was to link the biotic CH3Cl sink with the identity of active microorganisms and their biochemical pathways for CH3Cl degradation in a deciduous forest soil. When tested in laboratory microcosms, biological CH3Cl consumption occurred in leaf litter, senescent leaves, and organic and mineral soil horizons. Highest consumption rates, around 2 mmol CH3Cl g-1 dry weight h-1, were measured in organic soil and senescent leaves, suggesting that top soil layers are active (micro-)biological CH3Cl degradation compartments of forest ecosystems. The DNA of these [13C]-CH3Cl-degrading microbial communities was labelled using stable isotope probing (SIP), and the corresponding taxa and their metabolic pathways studied using high-throughput metagenomics sequencing analysis. [13C]-labelled Metagenome-Assembled Genome closely related to the family Beijerinckiaceae may represent a new methylotroph family of Alphaproteobacteria, which is found in metagenome databases of forest soils samples worldwide. Gene markers of the only known pathway for aerobic CH3Cl degradation, via the methyltransferase system encoded by the CH3Cl utilisation genes (cmu), were undetected in the DNA-SIP metagenome data, suggesting that biological CH3Cl sink in this deciduous forest soil operates by a cmu-independent metabolism.
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Affiliation(s)
- Eileen Kröber
- Max-Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany
- Microbial Biogeochemistry, RA Landscape Functioning, ZALF Leibniz Centre for Agricultural Landscape Research, Müncheberg, Germany
| | - Saranya Kanukollu
- Microbial Biogeochemistry, RA Landscape Functioning, ZALF Leibniz Centre for Agricultural Landscape Research, Müncheberg, Germany
| | - Sonja Wende
- Microbial Biogeochemistry, RA Landscape Functioning, ZALF Leibniz Centre for Agricultural Landscape Research, Müncheberg, Germany
| | - Françoise Bringel
- Génétique Moléculaire, Génomique, Microbiologie (GMGM), Université de Strasbourg, UMR 7156 CNRS, Strasbourg, France
| | - Steffen Kolb
- Microbial Biogeochemistry, RA Landscape Functioning, ZALF Leibniz Centre for Agricultural Landscape Research, Müncheberg, Germany
- Thaer Institute, Faculty of Life Sciences, Humboldt University of Berlin, Berlin, Germany
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Artuso I, Turrini P, Pirolo M, Lugli GA, Ventura M, Visca P. Phylogenomic Reconstruction and Metabolic Potential of the Genus Aminobacter. Microorganisms 2021; 9:microorganisms9061332. [PMID: 34205374 PMCID: PMC8235418 DOI: 10.3390/microorganisms9061332] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 12/01/2022] Open
Abstract
Bacteria belonging to the genus Aminobacter are metabolically versatile organisms thriving in both natural and anthropized terrestrial environments. To date, the taxonomy of this genus is poorly defined due to the unavailability of the genomic sequence of A. anthyllidis LMG 26462T and the presence of unclassified Aminobacter strains. Here, we determined the genome sequence of A. anthyllidis LMG 26462T and performed phylogenomic, average nucleotide identity and digital DNA-DNA hybridization analyses of 17 members of genus Aminobacter. Our results indicate that 16S rRNA-based phylogeny does not provide sufficient species-level discrimination, since most of the unclassified Aminobacter strains belong to valid Aminobacter species or are putative new species. Since some members of the genus Aminobacter can utilize certain C1 compounds, such as methylamines and methyl halides, a comparative genomic analysis was performed to characterize the genetic basis of some degradative/assimilative pathways in the whole genus. Our findings suggest that all Aminobacter species are heterotrophic methylotrophs able to generate the methylene tetrahydrofolate intermediate through multiple oxidative pathways of C1 compounds and convey it in the serine cycle. Moreover, all Aminobacter species carry genes implicated in the degradation of phosphonates via the C-P lyase pathway, whereas only A. anthyllidis LMG 26462T contains a symbiosis island implicated in nodulation and nitrogen fixation.
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Affiliation(s)
- Irene Artuso
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy; (I.A.); (P.T.)
| | - Paolo Turrini
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy; (I.A.); (P.T.)
| | - Mattia Pirolo
- Department of Veterinary and Animal Sciences, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg C, Denmark;
| | - Gabriele Andrea Lugli
- Laboratory of Probiogenomics, Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11a, 43124 Parma, Italy; (G.A.L.); (M.V.)
| | - Marco Ventura
- Laboratory of Probiogenomics, Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11a, 43124 Parma, Italy; (G.A.L.); (M.V.)
- Interdepartmental Research Centre “Microbiome Research Hub”, University of Parma, 43124 Parma, Italy
| | - Paolo Visca
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy; (I.A.); (P.T.)
- Correspondence: ; Tel.: +39-0657336347
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Artuso I, Turrini P, Pirolo M, Lucidi M, Tescari M, Visaggio D, Mansi A, Lugli GA, Ventura M, Visca P. Phylogenomic analysis and characterization of carbon monoxide utilization genes in the family Phyllobacteriaceae with reclassification of Aminobacter carboxidus (Meyer et al. 1993, Hördt et al. 2020) as Aminobacter lissarensis comb. nov. (McDonald et al. 2005). Syst Appl Microbiol 2021; 44:126199. [PMID: 33848814 DOI: 10.1016/j.syapm.2021.126199] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/27/2021] [Accepted: 03/09/2021] [Indexed: 12/13/2022]
Abstract
The monotypic carboxydophilic genus Carbophilus has recently been transferred to the genus Aminobacter within the family Phyllobacteriaceae, and Carbophilus carboxidus was renamed Aminobacter carboxidus (comb. nov.) [Hördt et al. 2020]. Due to the poor resolution of the 16S rRNA gene-based phylogeny, an extensive phylogenomic analysis of the family Phyllobacteriaceae was conducted, with particular focus on the genus Aminobacter. Whole genome-based analyses of Phyllobacteriaceae type strains provided evidenced that the genus Aminobacter forms a monophyletic cluster, clearly demarcated from all other members of the family. Close relatedness between A. carboxidus DSM 1086T and A. lissarensis DSM 17454T was inferred from core proteome phylogeny, shared gene content, and multilocus sequence analyses. ANI and GGDC provided genetic similarity values above the species demarcating threshold for these two type strains. Metabolic profiling and cell morphology analysis corroborated the phenotypic identity between A. carboxidus DSM 1086T and A. lissarensis DSM 17454T. Search for the presence of carbon monoxide dehydrogenase (CODH) genes in Phyllobacteriaceae genomes revealed that the form II CODH is widespread in the family, whereas form I CODH was detected in few Mesorhizobium type strains, and in both A. carboxidus DSM 1086T and A. lissarensis DSM 17454T. Results of phylogenomic, chemotaxonomic, and morphological investigations, combined with the presence of similarly arranged CODH genes, indicate that A. carboxidus DSM 1086T and A. lissarensis DSM 17454T are distinct strains of the same species. Hence A. carboxidus is a later subjective heterotypic synonym of A. lissarensis.
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Affiliation(s)
- Irene Artuso
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Paolo Turrini
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Mattia Pirolo
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Massimiliano Lucidi
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Marco Tescari
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Daniela Visaggio
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Antonella Mansi
- Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, Italian Workers' Compensation Authority (INAIL), Monte Porzio Catone, Rome, Italy
| | - Gabriele Andrea Lugli
- Laboratory of Probiogenomics, Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11a, 43124 Parma, Italy
| | - Marco Ventura
- Laboratory of Probiogenomics, Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11a, 43124 Parma, Italy
| | - Paolo Visca
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy.
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The ever-expanding limits of enzyme catalysis and biodegradation: polyaromatic, polychlorinated, polyfluorinated, and polymeric compounds. Biochem J 2021; 477:2875-2891. [PMID: 32797216 PMCID: PMC7428800 DOI: 10.1042/bcj20190720] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/29/2020] [Accepted: 07/31/2020] [Indexed: 11/17/2022]
Abstract
Biodegradation is simply the metabolism of anthropogenic, or otherwise unwanted, chemicals in our environment, typically by microorganisms. The metabolism of compounds commonly found in living things is limited to several thousand metabolites whereas ∼100 million chemical substances have been devised by chemical synthesis, and ∼100 000 are used commercially. Since most of those compounds are not natively found in living things, and some are toxic or carcinogenic, the question arises as to whether there is some organism somewhere with the enzymes that can biodegrade them. Repeatedly, anthropogenic chemicals have been denoted ‘non-biodegradable,’ only to find they are reactive with one or more enzyme(s). Enzyme reactivity has been organized into categories of functional group transformations. The discovery of new functional group transformations has continually expanded our knowledge of enzymes and biodegradation. This expansion of new-chemical biodegradation is driven by the evolution and spread of newly evolved enzymes. This review describes the biodegradation of widespread commercial chemicals with a focus on four classes: polyaromatic, polychlorinated, polyfluorinated, and polymeric compounds. Polyaromatic hydrocarbons include some of the most carcinogenic compounds known. Polychlorinated compounds include polychlorinated biphenyls (PCBs) and many pesticides of the twentieth century. Polyfluorinated compounds are a major focus of bioremediation efforts today. Polymers are clogging landfills, killing aquatic species in the oceans and increasingly found in our bodies. All of these classes of compounds, each thought at one time to be non-biodegradable, have been shown to react with natural enzymes. The known limits of enzyme catalysis, and hence biodegradation, are continuing to expand.
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Li X, Wang J, Wu W, Jia Y, Fan S, Hlaing TS, Khokhar I, Yan Y. Cometabolic biodegradation of quizalofop-p-ethyl by Methylobacterium populi YC-XJ1 and identification of QPEH1 esterase. ELECTRON J BIOTECHN 2020. [DOI: 10.1016/j.ejbt.2020.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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Li X, Wang J, Jia Y, Reheman A, Yan Y. The Genome Analysis of Methylobacterium populi YC-XJ1 with Diverse Xenobiotics Biodegrading Capacity and Degradation Characteristics of Related Hydrolase. Int J Mol Sci 2020; 21:ijms21124436. [PMID: 32580446 PMCID: PMC7352507 DOI: 10.3390/ijms21124436] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/15/2020] [Accepted: 06/17/2020] [Indexed: 11/16/2022] Open
Abstract
Methylobacterium populi YC-XJ1 isolated from desert soil exhibited a diverse degrading ability towards aromatic oxyphenoxypropionic acid esters (AOPPs) herbicide, phthalate esters (PAEs), organophosphorus flame retardants (OPFRs), chlorpyrifos and phoxim. The genome of YC-XJ1 was sequenced and analyzed systematically. YC-XJ1 contained a large number of exogenous compounds degradation pathways and hydrolase resources. The quizalofop-p-ethyl (QPE) degrading gene qpeh2 and diethyl phthalate (DEP) degrading gene deph1 were cloned and expressed. The characteristics of corresponding hydrolases were investigated. The specific activity of recombinant QPEH2 was 0.1 ± 0.02 U mg-1 for QPE with kcat/Km values of 1.8 ± 0.016 (mM-1·s-1). The specific activity of recombinant DEPH1 was 0.1 ± 0.02 U mg-1 for DEP with kcat/Km values of 0.8 ± 0.02 (mM-1·s-1). This work systematically illuminated the metabolic versatility of strain YC-XJ1 via the combination of genomics analysis and laboratory experiments. These results suggested that strain YC-XJ1 with diverse xenobiotics biodegrading capacity was a promising candidate for the bioremediation of polluted sites.
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Affiliation(s)
- Xianjun Li
- Graduate School, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (X.L.); (J.W.); (Y.J.)
| | - Junhuan Wang
- Graduate School, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (X.L.); (J.W.); (Y.J.)
| | - Yang Jia
- Graduate School, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (X.L.); (J.W.); (Y.J.)
| | - Aikebaier Reheman
- Key Laboratory of Toxicology, Ningde Normal University, Ningde 352100, China
- Correspondence: (A.R.); (Y.Y.); Tel.: +86-10-82109685 (Y.Y.)
| | - Yanchun Yan
- Graduate School, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (X.L.); (J.W.); (Y.J.)
- Correspondence: (A.R.); (Y.Y.); Tel.: +86-10-82109685 (Y.Y.)
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8
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Keppler F, Barnes JD, Horst A, Bahlmann E, Luo J, Nadalig T, Greule M, Hartmann SC, Vuilleumier S. Chlorine Isotope Fractionation of the Major Chloromethane Degradation Processes in the Environment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:1634-1645. [PMID: 31880153 DOI: 10.1021/acs.est.9b06139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Chloromethane (CH3Cl) is an important source of chlorine in the stratosphere, but detailed knowledge of the magnitude of its sources and sinks is missing. Here, we measured the stable chlorine isotope fractionation (εCl) associated with the major abiotic and biotic CH3Cl sinks in the environment, namely, CH3Cl degradation by hydroxyl (·OH) and chlorine (·Cl) radicals in the troposphere and by reference bacteria Methylorubrum extorquens CM4 and Leisingera methylohalidivorans MB2 from terrestrial and marine environments, respectively. No chlorine isotope fractionation was detected for reaction of CH3Cl with ·OH and ·Cl radicals, whereas a large chlorine isotope fractionation (εCl) of -10.9 ± 0.7‰ (n = 3) and -9.4 ± 0.9 (n = 3) was found for CH3Cl degradation by M. extorquens CM4 and L. methylohalidivorans MB2, respectively. The large difference in chlorine isotope fractionation observed between tropospheric and bacterial degradation of CH3Cl provides an effective isotopic tool to characterize and distinguish between major abiotic and biotic processes contributing to the CH3Cl sink in the environment. Our findings demonstrate the potential of emerging triple-element isotopic approaches including chlorine to carbon and hydrogen analysis for the assessment of global cycling of organochlorines.
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Affiliation(s)
- Frank Keppler
- Institute of Earth Sciences , Heidelberg University , Im Neuenheimer Feld 236 , 69120 Heidelberg , Germany
| | - Jaime D Barnes
- Department of Geological Sciences , University of Texas , Austin , Texas 78712 , United States
| | - Axel Horst
- Department of Isotope Biogeochemistry , Helmholtz Centre for Environmental Research - UFZ , Permoserstr.15 , 04318 Leipzig , Germany
| | - Enno Bahlmann
- Leibniz Institute for Baltic Sea Research Warnemünde , Seestrasse 15 , 18119 Rostock , Germany
| | - Jing Luo
- UMR 7156 CNRS Génétique Moléculaire, Génomique, Microbiologie , Université de Strasbourg , 4 allée Konrad Roentgen , 67000 Strasbourg , France
| | - Thierry Nadalig
- UMR 7156 CNRS Génétique Moléculaire, Génomique, Microbiologie , Université de Strasbourg , 4 allée Konrad Roentgen , 67000 Strasbourg , France
| | - Markus Greule
- Institute of Earth Sciences , Heidelberg University , Im Neuenheimer Feld 236 , 69120 Heidelberg , Germany
| | - S Christoph Hartmann
- Institute of Earth Sciences , Heidelberg University , Im Neuenheimer Feld 236 , 69120 Heidelberg , Germany
- Max Planck Institute for Chemistry , Hahn-Meitner-Weg 1 , 55128 Mainz , Germany
| | - Stéphane Vuilleumier
- UMR 7156 CNRS Génétique Moléculaire, Génomique, Microbiologie , Université de Strasbourg , 4 allée Konrad Roentgen , 67000 Strasbourg , France
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The Properties of 5-Methyltetrahydrofolate Dehydrogenase (MetF1) and Its Role in the Tetrahydrofolate-Dependent Dicamba Demethylation System in Rhizorhabdus dicambivorans Ndbn-20. J Bacteriol 2019; 201:JB.00096-19. [PMID: 31209079 DOI: 10.1128/jb.00096-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 06/13/2019] [Indexed: 11/20/2022] Open
Abstract
The herbicide dicamba is initially degraded via the tetrahydrofolate (THF)-dependent demethylation system in Rhizorhabdus dicambivorans Ndbn-20. Two THF-dependent dicamba methyltransferase gene clusters, scaffold 50 and scaffold 66, were found in the genome of strain Ndbn-20. Each cluster contains a dicamba methyltransferase gene and three THF metabolism-related genes, namely, metF (coding for 5,10-CH2-THF reductase), folD (coding for 5,10-CH2-THF dehydrogenase-5,10-methenyl-THF cyclohydrolase), and purU (coding for 10-formyl-THF deformylase). In this study, reverse transcription-PCR (RT-PCR) results showed that only genes in scaffold 66, not those in scaffold 50, were transcribed in dicamba-cultured cells. The metF gene of scaffold 66 (metF1) was expressed in Escherichia coli BL21(DE3), and the product was purified as a His6-tagged protein. Purified MetF1 was found to be a monomer and exhibited 5-CH3-THF dehydrogenase activity in vitro The k cat and Km for 5-CH3-THF were 0.23 s-1 and 16.48 μM, respectively. However, 5,10-CH2-THF reductase activity was not detected for MetF1 under the conditions tested. Gene disruption results showed that metF1 is essential for dicamba degradation, whereas folD1 is dispensable.IMPORTANCE There are several THF-dependent methyltransferase genes and THF-metabolic genes in the genome of R. dicambivorans Ndbn-20; however, which genes are involved in dicamba demethylation and the mechanism underlying THF regeneration remain unknown. This study revealed that scaffold 66 is responsible for dicamba demethylation and that MetF1 physiologically catalyzes the dehydrogenation of 5-CH3-THF to 5,10-CH2-THF in the THF-dependent dicamba demethylation system in R. dicambivorans Ndbn-20. Furthermore, the results showed that MetF1 differs from previously characterized MetF in phylogenesis, biochemical properties, and catalytic activity; e.g., MetF1 in vitro did not show 5,10-CH2-THF reductase activity, which is the physiological function of Escherichia coli MetF. This study provides new insights into the mechanism of the THF-dependent methyltransferase system.
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Bhatt P, Pal K, Bhandari G, Barh A. Modelling of the methyl halide biodegradation in bacteria and its effect on environmental systems. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2019; 158:88-100. [PMID: 31378365 DOI: 10.1016/j.pestbp.2019.04.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/25/2019] [Accepted: 04/29/2019] [Indexed: 06/10/2023]
Abstract
Methyl halide group of pesticides are being used widely in past decades as fumigant but due to their hazardous effect, these pesticides are not sold directly. They are volatile and gaseous in nature and may easily come in the contact of trophosphere and stratosphere. In troposphere, they are harmful to the living beings; nevertheless, in stratosphere they react with ozone and degrade the ozone layers. In this study, we have investigated the in-silico pathways of methyl halide and its toxic effect on living systems like pest, humans and environment. Till date, limited studies provide the understanding of degradation of methyl halide and its effect on the environment. This leads to availability of scanty information for overall bio-magnifications of methyl halides at molecular and cellular level. The model developed in the present study explains how a volatile toxic compound not only affects living systems on earth but also on environmental layers. Hub nodes were also evaluated by investigating the developed model topologically. Methyl transferase system is identified as promising enzyme in response to degradation of methyl halides.
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Affiliation(s)
- Pankaj Bhatt
- Department of Microbiology, Dolphin (P.G) Institute of Biomedical and Natural Sciences Dehradun, Uttarakhand, India.
| | - Kalyanbrata Pal
- Department of Microbiology, Dolphin (P.G) Institute of Biomedical and Natural Sciences Dehradun, Uttarakhand, India
| | - Geeta Bhandari
- Sardar Bhagwan Singh University, Dehradun, Uttarakhand, India
| | - Anupam Barh
- ICAR-Directorate of Mushroom Research, Solan, H.P, India
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Chen G, Shouakar-Stash O, Phillips E, Justicia-Leon SD, Gilevska T, Sherwood Lollar B, Mack EE, Seger ES, Löffler FE. Dual Carbon-Chlorine Isotope Analysis Indicates Distinct Anaerobic Dichloromethane Degradation Pathways in Two Members of Peptococcaceae. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:8607-8616. [PMID: 29975517 DOI: 10.1021/acs.est.8b01583] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Dichloromethane (DCM) is a probable human carcinogen and frequent groundwater contaminant and contributes to stratospheric ozone layer depletion. DCM is degraded by aerobes harboring glutathione-dependent DCM dehalogenases; however, DCM contamination occurs in oxygen-deprived environments, and much less is known about anaerobic DCM metabolism. Some members of the Peptococcaceae family convert DCM to environmentally benign products including acetate, formate, hydrogen (H2), and inorganic chloride under strictly anoxic conditions. The current study applied stable carbon and chlorine isotope fractionation measurements to the axenic culture Dehalobacterium formicoaceticum and to the consortium RM comprising DCM degrader Candidatus Dichloromethanomonas elyunquensis. Degradation-associated carbon and chlorine isotope enrichment factors (εC and εCl) of -42.4 ± 0.7‰ and -5.3 ± 0.1‰, respectively, were measured in D. formicoaceticum cultures. A similar εCl of -5.2 ± 0.1‰, but a substantially lower εC of -18.3 ± 0.2‰, were determined for Ca. Dichloromethanomonas elyunquensis. The εC and εCl values resulted in distinctly different dual element C-Cl isotope correlations (ΛC/Cl = Δδ13C/Δδ37Cl) of 7.89 ± 0.12 and 3.40 ± 0.03 for D. formicoaceticum and Ca. Dichloromethanomonas elyunquensis, respectively. The distinct ΛC/Cl values obtained for the two cultures imply mechanistically distinct C-Cl bond cleavage reactions, suggesting that members of Peptococcaceae employ different pathways to metabolize DCM. These findings emphasize the utility of dual carbon-chlorine isotope analysis to pinpoint DCM degradation mechanisms and to provide an additional line of evidence that detoxification is occurring at DCM-contaminated sites.
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Affiliation(s)
- Gao Chen
- Center for Environmental Biotechnology, Department of Civil and Environmental Engineering, and Department of Microbiology , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Orfan Shouakar-Stash
- Isotope Tracer Technologies Inc. (IT2) , Waterloo , Ontario N2 V 1Z5 , Canada
- Department of Earth and Environmental Sciences , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
- School of Engineering , University of Guelph , Guelph , Ontario N1G 2W1 , Canada
| | - Elizabeth Phillips
- Department of Earth Sciences , University of Toronto , Toronto , Ontario M5S 3B1 , Canada
| | - Shandra D Justicia-Leon
- School of Biology , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Tetyana Gilevska
- Department of Earth Sciences , University of Toronto , Toronto , Ontario M5S 3B1 , Canada
| | | | - E Erin Mack
- DuPont Corporate Remediation Group , E. I. DuPont de Nemours and Company , Wilmington , Delaware 19805 , United States
| | - Edward S Seger
- The Chemours Company , Wilmington , Delaware 19899 , United States
| | - Frank E Löffler
- Center for Environmental Biotechnology, Department of Civil and Environmental Engineering, and Department of Microbiology , University of Tennessee , Knoxville , Tennessee 37996 , United States
- Oak Ridge National Laboratory (UT-ORNL) Joint Institute for Biological Sciences (JIBS) and Biosciences Division , University of Tennessee and Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Department of Biosystems Engineering and Soil Science , University of Tennessee , Knoxville , Tennessee 37996 , United States
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12
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Jaeger N, Besaury L, Kröber E, Delort AM, Greule M, Lenhart K, Nadalig T, Vuilleumier S, Amato P, Kolb S, Bringel F, Keppler F. Chloromethane Degradation in Soils: A Combined Microbial and Two-Dimensional Stable Isotope Approach. JOURNAL OF ENVIRONMENTAL QUALITY 2018; 47:254-262. [PMID: 29634809 DOI: 10.2134/jeq2017.09.0358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Chloromethane (CHCl, methyl chloride) is the most abundant volatile halocarbon in the atmosphere and involved in stratospheric ozone depletion. The global CHCl budget, and especially the CHCl sink from microbial degradation in soil, still involves large uncertainties. These may potentially be resolved by a combination of stable isotope analysis and bacterial diversity studies. We determined the stable isotope fractionation of CHCl hydrogen and carbon and investigated bacterial diversity during CHCl degradation in three soils with different properties (forest, grassland, and agricultural soils) and at different temperatures and headspace mixing ratios of CHCl. The extent of chloromethane degradation decreased in the order forest > grassland > agricultural soil. Rates ranged from 0.7 to 2.5 μg g dry wt. d for forest soil, from 0.1 to 0.9 μg g dry wt. d for grassland soil, and from 0.1 to 0.4 μg g dry wt. d for agricultural soil and increased with increasing temperature and CHCl supplementation. The measured mean stable hydrogen enrichment factor of CHCl of -50 ± 13‰ was unaffected by temperature, mixing ratio, or soil type. In contrast, the stable carbon enrichment factor depended on CHCl degradation rates and ranged from -38 to -11‰. Bacterial community composition correlated with soil properties was independent from CHCl degradation or isotope enrichment. Nevertheless, increased abundance after CHCl incubation was observed in 21 bacterial operational taxonomical units (OTUs at the 97% 16S RNA sequence identity level). This suggests that some of these bacterial taxa, although not previously associated with CHCl degradation, may play a role in the microbial CHCl sink in soil.
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13
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Chen G, Kleindienst S, Griffiths DR, Mack EE, Seger ES, Löffler FE. Mutualistic interaction between dichloromethane- and chloromethane-degrading bacteria in an anaerobic mixed culture. Environ Microbiol 2017; 19:4784-4796. [DOI: 10.1111/1462-2920.13945] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 09/19/2017] [Accepted: 09/22/2017] [Indexed: 01/02/2023]
Affiliation(s)
- Gao Chen
- Center for Environmental Biotechnology; University of Tennessee; Knoxville TN 37996 USA
- Department of Civil and Environmental Engineering; University of Tennessee; Knoxville TN 37996 USA
| | - Sara Kleindienst
- Center for Environmental Biotechnology; University of Tennessee; Knoxville TN 37996 USA
- Oak Ridge National Laboratory; University of Tennessee and Oak Ridge National Laboratory (UT-ORNL) Joint Institute for Biological Sciences (JIBS) and Biosciences Division; Oak Ridge TN 37831 USA
- Center for Applied Geosciences; Department of Geosciences, Eberhard Karls University Tübingen; Tübingen 72074 Germany
| | | | - E. Erin Mack
- Corporate Remediation Group; E. I. DuPont de Nemours and Company; Wilmington DE 19805 USA
| | | | - Frank E. Löffler
- Center for Environmental Biotechnology; University of Tennessee; Knoxville TN 37996 USA
- Department of Civil and Environmental Engineering; University of Tennessee; Knoxville TN 37996 USA
- Oak Ridge National Laboratory; University of Tennessee and Oak Ridge National Laboratory (UT-ORNL) Joint Institute for Biological Sciences (JIBS) and Biosciences Division; Oak Ridge TN 37831 USA
- Department of Microbiology; University of Tennessee; Knoxville TN 37996 USA
- Department of Biosystems Engineering and Soil Science; University of Tennessee; Knoxville TN 37996 USA
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14
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Karwautz C, Kus G, Stöckl M, Neu TR, Lueders T. Microbial megacities fueled by methane oxidation in a mineral spring cave. ISME JOURNAL 2017; 12:87-100. [PMID: 28949325 PMCID: PMC5739006 DOI: 10.1038/ismej.2017.146] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/23/2017] [Accepted: 08/01/2017] [Indexed: 12/18/2022]
Abstract
Massive biofilms have been discovered in the cave of an iodine-rich former medicinal spring in southern Germany. The biofilms completely cover the walls and ceilings of the cave, giving rise to speculations about their metabolism. Here we report on first insights into the structure and function of the biofilm microbiota, combining geochemical, imaging and molecular analytics. Stable isotope analysis indicated that thermogenic methane emerging into the cave served as an important driver of biofilm formation. The undisturbed cavern atmosphere contained up to 3000 p.p.m. methane and was microoxic. A high abundance and diversity of aerobic methanotrophs primarily within the Methylococcales (Gammaproteobacteria) and methylotrophic Methylophilaceae (Betaproteobacteria) were found in the biofilms, along with a surprising diversity of associated heterotrophic bacteria. The highest methane oxidation potentials were measured for submerged biofilms on the cavern wall. Highly organized globular structures of the biofilm matrix were revealed by fluorescent lectin staining. We propose that the extracellular matrix served not only as an electron sink for nutrient-limited biofilm methylotrophs but potentially also as a diffusive barrier against volatilized iodine species. Possible links between carbon and iodine cycling in this peculiar habitat are discussed.
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Affiliation(s)
- Clemens Karwautz
- Institute of Groundwater Ecology, Helmholtz Zentrum München - German Research Centre for Environmental Health, Neuherberg, Germany
| | - Günter Kus
- Bavarian Environment Agency (LfU), Department 10: Geological Survey, Hof/Saale, Germany
| | - Michael Stöckl
- Institute of Groundwater Ecology, Helmholtz Zentrum München - German Research Centre for Environmental Health, Neuherberg, Germany
| | - Thomas R Neu
- Department of River Ecology, Helmholtz Centre for Environmental Research-UFZ, Magdeburg, Germany
| | - Tillmann Lueders
- Institute of Groundwater Ecology, Helmholtz Zentrum München - German Research Centre for Environmental Health, Neuherberg, Germany
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15
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Yeager CM, Amachi S, Grandbois R, Kaplan DI, Xu C, Schwehr KA, Santschi PH. Microbial Transformation of Iodine: From Radioisotopes to Iodine Deficiency. ADVANCES IN APPLIED MICROBIOLOGY 2017; 101:83-136. [PMID: 29050668 DOI: 10.1016/bs.aambs.2017.07.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Iodine is a biophilic element that is important for human health, both as an essential component of several thyroid hormones and, on the other hand, as a potential carcinogen in the form of radioiodine generated by anthropogenic nuclear activity. Iodine exists in multiple oxidation states (-1, 0, +1, +3, +5, and +7), primarily as molecular iodine (I2), iodide (I-), iodate [Formula: see text] , or organic iodine (org-I). The mobility of iodine in the environment is dependent on its speciation and a series of redox, complexation, sorption, precipitation, and microbial reactions. Over the last 15years, there have been significant advances in iodine biogeochemistry, largely spurred by renewed interest in the fate of radioiodine in the environment. We review the biogeochemistry of iodine, with particular emphasis on the microbial processes responsible for volatilization, accumulation, oxidation, and reduction of iodine, as well as the exciting technological potential of these fascinating microorganisms and enzymes.
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16
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Rodrigo-Torres L, Pujalte MJ, Arahal DR. Draft genome of Leisingera aquaemixtae CECT 8399(T), a member of the Roseobacter clade isolated from a junction of fresh and ocean water in Jeju Island, South Korea. GENOMICS DATA 2016; 7:233-6. [PMID: 26981415 PMCID: PMC4778666 DOI: 10.1016/j.gdata.2016.01.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 01/08/2016] [Accepted: 01/14/2016] [Indexed: 10/26/2022]
Abstract
We report the draft genome sequence and annotation of Leisingera aquaemixtae CECT 8399(T) (DDBJ/EMBL/GenBank accession number CYSR00000000) which comprises 4,614,060 bp, 4313 protein coding genes, 54 tRNA coding genes and 7 rRNA coding genes. General findings of the annotated genome, such as pigment indigoidine operon, phenylacetate oxidation genes or predictable number of replicons, are commented in comparison to other Leisingera species. Average Nucleotide Identity between available genomes of type strains of species of Leisingera and Phaeobacter genera has been calculated to evaluate its current classification.
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Affiliation(s)
- Lidia Rodrigo-Torres
- Departamento de Microbiología y Ecología, Universidad de Valencia, Valencia, Spain
| | - María J Pujalte
- Departamento de Microbiología y Ecología, Universidad de Valencia, Valencia, Spain
| | - David R Arahal
- Departamento de Microbiología y Ecología, Universidad de Valencia, Valencia, Spain
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17
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Coleman NV. Primers: Functional Genes for Aerobic Chlorinated Hydrocarbon-Degrading Microbes. SPRINGER PROTOCOLS HANDBOOKS 2015. [DOI: 10.1007/8623_2015_91] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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18
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Yang G, Ding Y. Recent advances in biocatalyst discovery, development and applications. Bioorg Med Chem 2014; 22:5604-12. [DOI: 10.1016/j.bmc.2014.06.033] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 06/13/2014] [Accepted: 06/17/2014] [Indexed: 12/25/2022]
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19
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Buddruhs N, Chertkov O, Petersen J, Fiebig A, Chen A, Pati A, Ivanova N, Lapidus A, Goodwin LA, Chain P, Detter JC, Gronow S, Kyrpides NC, Woyke T, Göker M, Brinkhoff T, Klenk HP. Complete genome sequence of the marine methyl-halide oxidizing Leisingera methylohalidivorans type strain (DSM 14336(T)), a representative of the Roseobacter clade. Stand Genomic Sci 2013; 9:128-41. [PMID: 24501651 PMCID: PMC3910543 DOI: 10.4056/sigs.4297965] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Leisingera methylohalidivorans Schaefer et al. 2002 emend. Vandecandelaere et al. 2008 is the type species of the genus Leisingera. The genus belongs to the Roseobacter clade (Rhodobacteraceae, Alphaproteobacteria), a widely distributed lineage in marine environments. Leisingera and particularly L. methylohalidivorans strain MB2(T) is of special interest due to its methylotrophy. Here we describe the complete genome sequence and annotation of this bacterium together with previously unreported aspects of its phenotype. The 4,650,996 bp long genome with its 4,515 protein-coding and 81 RNA genes consists of three replicons, a single chromosome and two extrachromosomal elements with sizes of 221 kb and 285 kb.
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Affiliation(s)
- Nora Buddruhs
- Leibniz-Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Olga Chertkov
- Los Alamos National Laboratory, Bioscience Division, Los Alamos, New Mexico, USA
| | - Jörn Petersen
- Leibniz-Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Anne Fiebig
- Leibniz-Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Amy Chen
- Biological Data Management and Technology Center, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Amrita Pati
- DOE Joint Genome Institute, Walnut Creek, California, USA
| | | | - Alla Lapidus
- Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg, Russia ; Algorithmic Biology Lab, St. Petersburg Academic University, St.Petersburg, Russia
| | - Lynne A Goodwin
- Los Alamos National Laboratory, Bioscience Division, Los Alamos, New Mexico, USA ; DOE Joint Genome Institute, Walnut Creek, California, USA
| | - Patrick Chain
- Los Alamos National Laboratory, Bioscience Division, Los Alamos, New Mexico, USA
| | - John C Detter
- Los Alamos National Laboratory, Bioscience Division, Los Alamos, New Mexico, USA ; DOE Joint Genome Institute, Walnut Creek, California, USA
| | - Sabine Gronow
- Leibniz-Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | | | - Tanja Woyke
- DOE Joint Genome Institute, Walnut Creek, California, USA
| | - Markus Göker
- Biological Data Management and Technology Center, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Thorsten Brinkhoff
- Institute for Chemistry and Biology of the Marine Environment (ICMB), Oldenburg, Germany
| | - Hans-Peter Klenk
- Leibniz-Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
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20
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Cox MJ, Schäfer H, Nightingale PD, McDonald IR, Murrell JC. Diversity of methyl halide-degrading microorganisms in oceanic and coastal waters. FEMS Microbiol Lett 2012; 334:111-8. [DOI: 10.1111/j.1574-6968.2012.02624.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 06/19/2012] [Accepted: 06/20/2012] [Indexed: 11/28/2022] Open
Affiliation(s)
- Michael J. Cox
- School of Life Sciences; University of Warwick; Coventry; UK
| | - Hendrik Schäfer
- School of Life Sciences; University of Warwick; Coventry; UK
| | | | - Ian R. McDonald
- Department of Biological Sciences; University of Waikato; Hamilton; New Zealand
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21
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Khan MAH, Whelan ME, Rhew RC. Effects of temperature and soil moisture on methyl halide and chloroform fluxes from drained peatland pasture soils. ACTA ACUST UNITED AC 2012; 14:241-9. [DOI: 10.1039/c1em10639b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Simonsen A, Badawi N, Anskjær GG, Albers CN, Sørensen SR, Sørensen J, Aamand J. Intermediate accumulation of metabolites results in a bottleneck for mineralisation of the herbicide metabolite 2,6-dichlorobenzamide (BAM) by Aminobacter spp. Appl Microbiol Biotechnol 2011; 94:237-45. [DOI: 10.1007/s00253-011-3591-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 08/22/2011] [Accepted: 09/17/2011] [Indexed: 11/25/2022]
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23
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Paul C, Pohnert G. Production and role of volatile halogenated compounds from marine algae. Nat Prod Rep 2010; 28:186-95. [PMID: 21125112 DOI: 10.1039/c0np00043d] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Carsten Paul
- Friedrich Schiller University Jena, Department for Bioorganic Analytics, Lessingstraße 8, 07743, Jena, Germany
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24
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Chistoserdova L, Kalyuzhnaya MG, Lidstrom ME. The expanding world of methylotrophic metabolism. Annu Rev Microbiol 2009; 63:477-99. [PMID: 19514844 DOI: 10.1146/annurev.micro.091208.073600] [Citation(s) in RCA: 261] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the past few years, the field of methylotrophy has undergone a significant transformation in terms of discovery of novel types of methylotrophs, novel modes of methylotrophy, and novel metabolic pathways. This time has also been marked by the resolution of long-standing questions regarding methylotrophy and the challenge of long-standing dogmas. This chapter is not intended to provide a comprehensive review of metabolism of methylotrophic bacteria. Instead we focus on significant recent discoveries that are both refining and transforming the current understanding of methylotrophy as a metabolic phenomenon. We also review new directions in methylotroph ecology that improve our understanding of the role of methylotrophy in global biogeochemical processes, along with an outlook for the future challenges in the field.
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Affiliation(s)
- Ludmila Chistoserdova
- Departments of Chemical Engineering, University of Washington, Seattle, Washington 98195, USA
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25
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Trotsenko YA, Torgonskaya ML. The aerobic degradation of dichloromethane: Structural-functional aspects (a review). APPL BIOCHEM MICRO+ 2009. [DOI: 10.1134/s0003683809030016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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26
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Substrate-specific clades of active marine methylotrophs associated with a phytoplankton bloom in a temperate coastal environment. Appl Environ Microbiol 2008; 74:7321-8. [PMID: 18849453 DOI: 10.1128/aem.01266-08] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Marine microorganisms that consume one-carbon (C(1)) compounds are poorly described, despite their impact on global climate via an influence on aquatic and atmospheric chemistry. This study investigated marine bacterial communities involved in the metabolism of C(1) compounds. These communities were of relevance to surface seawater and atmospheric chemistry in the context of a bloom that was dominated by phytoplankton known to produce dimethylsulfoniopropionate. In addition to using 16S rRNA gene fingerprinting and clone libraries to characterize samples taken from a bloom transect in July 2006, seawater samples from the phytoplankton bloom were incubated with (13)C-labeled methanol, monomethylamine, dimethylamine, methyl bromide, and dimethyl sulfide to identify microbial populations involved in the turnover of C(1) compounds, using DNA stable isotope probing. The [(13)C]DNA samples from a single time point were characterized and compared using denaturing gradient gel electrophoresis (DGGE), fingerprint cluster analysis, and 16S rRNA gene clone library analysis. Bacterial community DGGE fingerprints from (13)C-labeled DNA were distinct from those obtained with the DNA of the nonlabeled community DNA and suggested some overlap in substrate utilization between active methylotroph populations growing on different C(1) substrates. Active methylotrophs were affiliated with Methylophaga spp. and several clades of undescribed Gammaproteobacteria that utilized methanol, methylamines (both monomethylamine and dimethylamine), and dimethyl sulfide. rRNA gene sequences corresponding to populations assimilating (13)C-labeled methyl bromide and other substrates were associated with members of the Alphaproteobacteria (e.g., the family Rhodobacteraceae), the Cytophaga-Flexibacter-Bacteroides group, and unknown taxa. This study expands the known diversity of marine methylotrophs in surface seawater and provides a comprehensive data set for focused cultivation and metagenomic analyses in the future.
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27
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Fasan R, Meharenna YT, Snow CD, Poulos TL, Arnold FH. Evolutionary history of a specialized p450 propane monooxygenase. J Mol Biol 2008; 383:1069-80. [PMID: 18619466 DOI: 10.1016/j.jmb.2008.06.060] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 06/13/2008] [Accepted: 06/19/2008] [Indexed: 11/16/2022]
Abstract
The evolutionary pressures that shaped the specificity and catalytic efficiency of enzymes can only be speculated. While directed evolution experiments show that new functions can be acquired under positive selection with few mutations, the role of negative selection in eliminating undesired activities and achieving high specificity remains unclear. Here we examine intermediates along the 'lineage' from a naturally occurring C12-C20 fatty acid hydroxylase (P450BM3) to a laboratory-evolved P450 propane monooxygenase (P450PMO) having 20 heme domain substitutions compared to P450BM3. Biochemical, crystallographic, and computational analyses show that a minimal perturbation of the P450BM3 fold and substrate-binding pocket accompanies a significant broadening of enzyme substrate range and the emergence of propane activity. In contrast, refinement of the enzyme catalytic efficiency for propane oxidation (approximately 9000-fold increase in kcat/Km) involves profound reshaping and partitioning of the substrate access pathway. Remodeling of the substrate-recognition mechanisms ultimately results in remarkable narrowing of the substrate profile around propane and enables the acquisition of a basal iodomethane dehalogenase activity as yet unknown in natural alkane monooxygenases. A highly destabilizing L188P substitution in a region of the enzyme that undergoes a large conformational change during catalysis plays an important role in adaptation to the gaseous alkane. This work demonstrates that positive selection alone is sufficient to completely respecialize the cytochrome P450 for function on a nonnative substrate.
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Affiliation(s)
- Rudi Fasan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., MC 210-41, Pasadena, CA 91125, USA
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28
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Planktonic and sediment-associated aerobic methanotrophs in two seep systems along the North American margin. Appl Environ Microbiol 2008; 74:3985-95. [PMID: 18487407 DOI: 10.1128/aem.00069-08] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methane vents are of significant geochemical and ecological importance. Notable progress has been made toward understanding anaerobic methane oxidation in marine sediments; however, the diversity and distribution of aerobic methanotrophs in the water column are poorly characterized. Both environments play an essential role in regulating methane release from the oceans to the atmosphere. In this study, the diversity of particulate methane monooxygenase (pmoA) and 16S rRNA genes from two methane vent environments along the California continental margin was characterized. The pmoA phylotypes recovered from methane-rich sediments and the overlying water column differed. Sediments harbored the greatest number of unique pmoA phylotypes broadly affiliated with the Methylococcaceae family, whereas planktonic pmoA phylotypes formed three clades that were distinct from the sediment-hosted methanotrophs and distantly related to established methanotrophic clades. Water column-associated phylotypes were highly similar between field sites, suggesting that planktonic methanotroph diversity is controlled primarily by environmental factors rather than geographical proximity. Analysis of 16S rRNA genes from methane-rich waters did not readily recover known methanotrophic lineages, with only a few phylotypes demonstrating distant relatedness to Methylococcus. The development of new pmo primers increased the recovery of monooxygenase genes from the water column and led to the discovery of a highly diverged monooxygenase sequence which is phylogenetically intermediate to Amo and pMMO. This sequence potentiates insight into the amo/pmo superfamily. Together, these findings lend perspective into the diversity and segregation of aerobic methanotrophs within different methane-rich habitats in the marine environment.
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29
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Guo X, Lidstrom ME. Metabolite profiling analysis ofMethylobacterium extorquens AM1 by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry. Biotechnol Bioeng 2008; 99:929-40. [PMID: 17879968 DOI: 10.1002/bit.21652] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Methylobacterium extorquens AM1 is a facultative methylotroph, which is a potential candidate to be used in commercial processes to convert simple one-carbon compounds to a variety of multicarbon chemicals and products. To better understand C(1) metabolism in M. extorquens AM1 at the systems level, metabolite profiling tools were developed and applied in this bacterium. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC x GC-TOFMS) was used to obtain metabolite profiles of M. extorquens AM1 (primarily organic acids) and to identify the metabolite differences between cells grown on methanol (C(1) substrate) and succinate (multicarbon substrate). In this study, a list of compounds that included amino acids and major intermediates of central C(1) and multicarbon metabolism were studied as target metabolites. For these, calibration curves were obtained for absolute quantification by spiking different amounts of standard mixtures to cell cultures. Parallel factor analysis (PARAFAC) was used for accurate peak quantification. Unknown chemical differences between cells grown on methanol and succinate were identified by applying Fisher ratio analysis at a selective mass channel (m/z 147). Thirty-six compounds were discovered to be statistically differentially expressed between C(1) and multicarbon metabolism. Among these, 13 were identified by matching to library mass spectra, and the rest were novel compounds that were not included in libraries. These differentially expressed compounds have provided clues to new pathways that are specifically linked to C(1) metabolism.
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Affiliation(s)
- Xiaofeng Guo
- Department of Chemical Engineering, University of Washington, Box 3521, Seattle, Washington 98195-2180, USA
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30
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Schäfer H, Miller LG, Oremland RS, Murrell JC. Bacterial Cycling of Methyl Halides. ADVANCES IN APPLIED MICROBIOLOGY 2007; 61:307-46. [PMID: 17448794 DOI: 10.1016/s0065-2164(06)61009-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Hendrik Schäfer
- Department of Biological Sciences, University of Warwick, Coventry, United Kingdom
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31
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Nercessian O, Kalyuzhnaya MG, Joye SB, Lidstrom ME, Chistoserdova L. Analysis of fae and fhcD genes in Mono Lake, California. Appl Environ Microbiol 2006; 71:8949-53. [PMID: 16332897 PMCID: PMC1317423 DOI: 10.1128/aem.71.12.8949-8953.2005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genes for two enzymes of the tetrahydromethanopterin-linked C(1) transfer pathway (fae and fhcD) were detected in hypersaline, hyperalkaline Mono Lake (California), via PCR amplification and analysis. Low diversity for fae and fhcD was noted, in contrast to the diversity previously detected in a freshwater lake, Lake Washington (Washington).
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Affiliation(s)
- Olivier Nercessian
- Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
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32
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Nikolausz M, Nijenhuis I, Ziller K, Richnow HH, Kästner M. Stable carbon isotope fractionation during degradation of dichloromethane by methylotrophic bacteria. Environ Microbiol 2006; 8:156-64. [PMID: 16343330 DOI: 10.1111/j.1462-2920.2005.00878.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Stable carbon isotope fractionation during dichloromethane (DCM) degradation by methylotrophic bacteria was investigated under aerobic and nitrate-reducing conditions. The strains studied comprise several Hyphomicrobium strains, Methylobacterium, Methylopila, Methylophilus and Methylorhabdus spp. that are considered to degrade DCM by a glutathione (GSH)-dependent dehalogenase enzyme system in the initial step. The stable carbon isotope fractionation factors (alphaC) of the strains varied under aerobic conditions between 1.043 and 1.071 and under nitrate-reducing conditions between 1.048 and 1.065. Comparison of isotope fractionation under aerobic and nitrate-reducing conditions by individual strains revealed only minor to no differences. The variability in isotope fractionation among strains was found to be related to the polymorphism of the functional genes encoding the DCM dehalogenase.
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Affiliation(s)
- Marcell Nikolausz
- Department of Bioremediation, UFZ-Centre for Environmental Research Leipzig-Halle GmbH, Permoserstr. 15, D-04318 Leipzig, Germany
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McDonald IR, Kämpfer P, Topp E, Warner KL, Cox MJ, Hancock TLC, Miller LG, Larkin MJ, Ducrocq V, Coulter C, Harper DB, Murrell JC, Oremland RS. Aminobacter ciceronei sp. nov. and Aminobacter lissarensis sp. nov., isolated from various terrestrial environments. Int J Syst Evol Microbiol 2005; 55:1827-1832. [PMID: 16166673 DOI: 10.1099/ijs.0.63716-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The bacterial strains IMB-1(T) and CC495(T), which are capable of growth on methyl chloride (CH(3)Cl, chloromethane) and methyl bromide (CH(3)Br, bromomethane), were isolated from agricultural soil in California fumigated with CH(3)Br, and woodland soil in Northern Ireland, respectively. Two pesticide-/herbicide-degrading bacteria, strains ER2 and C147, were isolated from agricultural soil in Canada. Strain ER2 degrades N-methyl carbamate insecticides, and strain C147 degrades triazine herbicides widely used in agriculture. On the basis of their morphological, physiological and genotypic characteristics, these four strains are considered to represent two novel species of the genus Aminobacter, for which the names Aminobacter ciceronei sp. nov. (type strain IMB-1(T)=ATCC 202197(T)=CIP 108660(T)=CCUG 50580(T); strains ER2 and C147) and Aminobacter lissarensis sp. nov. (type strain CC495(T)=NCIMB 13798(T)=CIP 108661(T)=CCUG 50579(T)) are proposed.
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Affiliation(s)
- Ian R McDonald
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Peter Kämpfer
- Institut für Angewandte Mikrobiologie, Justus-Liebig-Universität Giessen, D-35390 Giessen, Germany
| | - Ed Topp
- Agriculture and Agri-Food Canada, London, Ontario, Canada N5V 4T3
| | - Karen L Warner
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Michael J Cox
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | | | - Laurence G Miller
- US Geological Survey, 345 Middlefield Rd, MS 480, Menlo Park, CA 94025, USA
| | | | | | - Catherine Coulter
- School of Agriculture and Food Science, Queen's University Belfast, Newforge Lane, Belfast BT9 5PX, UK
| | - David B Harper
- School of Agriculture and Food Science, Queen's University Belfast, Newforge Lane, Belfast BT9 5PX, UK
| | - J Colin Murrell
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Ronald S Oremland
- US Geological Survey, 345 Middlefield Rd, MS 480, Menlo Park, CA 94025, USA
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Nercessian O, Noyes E, Kalyuzhnaya MG, Lidstrom ME, Chistoserdova L. Bacterial populations active in metabolism of C1 compounds in the sediment of Lake Washington, a freshwater lake. Appl Environ Microbiol 2005; 71:6885-99. [PMID: 16269723 PMCID: PMC1287692 DOI: 10.1128/aem.71.11.6885-6899.2005] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Accepted: 06/13/2005] [Indexed: 11/20/2022] Open
Abstract
Active members of the bacterial community in the sediment of Lake Washington, with special emphasis on C1 utilizers, were identified by employing two complementary culture-independent approaches: reverse transcription of environmental mRNA and 16S rRNA combined with PCR (RT-PCR) and stable-isotope probing (SIP) of DNA with the 13C-labeled C1 substrates methanol, methylamine, formaldehyde, and formate. Analysis of RT-PCR-amplified fragments of 16S rRNA-encoding genes revealed that gammaproteobacterial methanotrophs belonging to Methylobacter and Methylomonas dominate the active methylotroph population, while only one other known methylotrophic lineage, Methylophilaceae, was detected via this approach. Analysis of RT-PCR-amplified functional genes, pmoA and fae, allowed detection of alphaproteobacterial (Methylosinus) and gammaproteobacterial (Methylobacter, Methylomonas, and Methylomicrobium) methanotrophs, methylotrophs of the genus Methylobacterium, and yet-unidentified proteobacteria. SIP experiments allowed detection of a broad variety of groups actively metabolizing C1 compounds. Comparisons between 16S rRNA gene pools amplified from [13C]DNA and from [12C]DNA revealed that the proportion of Methylophilus-related sequences increased in the presence of [13C]methanol, [13C]methylamine, and [13C]formaldehyde; Novosphingobium-related sequences were enriched in the presence of [13C]methanol; Gemmatimonadaceae-related sequences were enriched in the presence of [13C]formaldehyde and [13C]formate; and Xanthomonadaceae-related sequences were enriched in the presence of [13C]formate. Analysis of fae genes amplified from [13C]DNAs isolated from different microcosms revealed specific shifts in populations in response to a specific C1 compound: Methylosinus sequences dominated the [13C]methanol microcosm pool, and beta- and gammaproteobacterial sequences dominated the [13C]methylamine microcosm pool. The [13C]formaldehyde microcosm was dominated by betaproteobacterial sequences and by sequences of a nonaffiliated group, while the [13C]formate microcosm was dominated by alpha- and betaproteobacterial sequences. Overall, these data point toward the presence of a diverse population of active methylotrophs in Lake Washington sediments and toward the existence of yet-uncultivated organisms.
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Affiliation(s)
- Olivier Nercessian
- Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
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Borodina E, Cox MJ, McDonald IR, Murrell JC. Use of DNA-stable isotope probing and functional gene probes to investigate the diversity of methyl chloride-utilizing bacteria in soil. Environ Microbiol 2005; 7:1318-28. [PMID: 16104855 DOI: 10.1111/j.1462-5822.2005.00819.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Enrichment and isolation of methyl chloride-utilizing bacteria from various terrestrial environments, including woodland and forest soils, resulted in the identification of seven methyl chloride-utilizing strains belonging to the genus Hyphomicrobium, an Aminobacter strain TW23 and strain WG1, which grouped closely with the genus Mesorhizobium. Methyl chloride enrichment cultures were dominated by Hyphomicrobium species, indicating that these bacteria were most suited to growth under the enrichment and isolation conditions used. However, the application of culture-independent techniques such as DNA-stable isotope probing and the use of a functional gene probe targeting cmuA, which encodes the methyltransferase catalysing the first step in bacterial methyl chloride metabolism, indicated a greater diversity of methyl chloride-utilizing bacteria in the terrestrial environment, compared with the diversity of soil isolates obtained via the enrichment and isolation procedure. It also revealed the presence of as yet uncultured and potentially novel methyl chloride-degrading bacteria in soil.
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Affiliation(s)
- Elena Borodina
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
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Goodwin KD, Tokarczyk R, Stephens FC, Saltzman ES. Description of toluene inhibition of methyl bromide biodegradation in seawater and isolation of a marine toluene oxidizer that degrades methyl bromide. Appl Environ Microbiol 2005; 71:3495-503. [PMID: 16000753 PMCID: PMC1169029 DOI: 10.1128/aem.71.7.3495-3503.2005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methyl bromide (CH3Br) and methyl chloride (CH3Cl) are important precursors for destruction of stratospheric ozone, and oceanic uptake is an important component of the biogeochemical cycle of these methyl halides. In an effort to identify and characterize the organisms mediating halocarbon biodegradation, we surveyed the effect of potential cometabolic substrates on CH3Br biodegradation using a 13CH3Br incubation technique. Toluene (160 to 200 nM) clearly inhibited CH3Br and CH3Cl degradation in seawater samples from the North Atlantic, North Pacific, and Southern Oceans. Furthermore, a marine bacterium able to co-oxidize CH3Br while growing on toluene was isolated from subtropical Western Atlantic seawater. The bacterium, Oxy6, was also able to oxidize o-xylene and the xylene monooxygenase (XMO) pathway intermediate 3-methylcatechol. Patterns of substrate oxidation, lack of acetylene inhibition, and the inability of the toluene 4-monooxygenase (T4MO)-containing bacterium Pseudomonas mendocina KR1 to degrade CH3Br ruled out participation of the T4MO pathway in Oxy6. Oxy6 also oxidized a variety of toluene (TOL) pathway intermediates such as benzyl alcohol, benzylaldehyde, benzoate, and catechol, but the inability of Pseudomonas putida mt-2 to degrade CH3Br suggested that the TOL pathway might not be responsible for CH3Br biodegradation. Molecular phylogenetic analysis identified Oxy6 to be a member of the family Sphingomonadaceae related to species within the Porphyrobacter genus. Although some Sphingomonadaceae can degrade a variety of xenobiotic compounds, this appears to be the first report of CH3Br degradation for this class of organism. The widespread inhibitory effect of toluene on natural seawater samples and the metabolic capabilities of Oxy6 indicate a possible link between aromatic hydrocarbon utilization and the biogeochemical cycle of methyl halides.
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Affiliation(s)
- Kelly D Goodwin
- National Oceanographic and Atmospheric Administration, Atlantic Oceanographic and Meteorological Laboratories, Ocean Chemistry Division, 4301 Rickenbacker Cswy., Miami, FL 33149, USA.
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Schäfer H, McDonald IR, Nightingale PD, Murrell JC. Evidence for the presence of a CmuA methyltransferase pathway in novel marine methyl halide-oxidizing bacteria. Environ Microbiol 2005; 7:839-52. [PMID: 15892703 DOI: 10.1111/j.1462-2920.2005.00757.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Marine bacteria that oxidized methyl bromide and methyl chloride were enriched and isolated from seawater samples. Six methyl halide-oxidizing enrichments were established from which 13 isolates that grew on methyl bromide and methyl chloride as sole sources of carbon and energy were isolated and maintained. All isolates belonged to three different clades in the Roseobacter group of the alpha subdivision of the Proteobacteria and were distinct from Leisingera methylohalidivorans, the only other identified marine bacterium that grows on methyl bromide as sole source of carbon and energy. Genes encoding the methyltransferase/corrinoid-binding protein CmuA, which is responsible for the initial step of methyl chloride oxidation in terrestrial methyl halide-oxidizing bacteria, were detected in enrichments and some of the novel marine strains. Gene clusters containing cmuA and other genes implicated in the metabolism of methyl halides were cloned from two of the isolates. Expression of CmuA during growth on methyl halides was demonstrated by analysis of polypeptides expressed during growth on methyl halides by SDS-PAGE and mass spectrometry in two isolates representing two of the three clades. These findings indicate that certain marine methyl halide degrading bacteria from the Roseobacter group contain a methyltransferase pathway for oxidation of methyl bromide that may be similar to that responsible for methyl chloride oxidation in Methylobacterium chloromethanicum. This pathway therefore potentially contributes to cycling of methyl halides in both terrestrial and marine environments.
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Affiliation(s)
- Hendrik Schäfer
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, England, UK
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Abstract
Stable isotope probing (SIP) is a technique that is used to identify the microorganisms in environmental samples that use a particular growth substrate. The method relies on the incorporation of a substrate that is highly enriched in a stable isotope, such as (13)C, and the identification of active microorganisms by the selective recovery and analysis of isotope-enriched cellular components. DNA and rRNA are the most informative taxonomic biomarkers and (13)C-labelled molecules can be purified from unlabelled nucleic acid by density-gradient centrifugation. The future holds great promise for SIP, particularly when combined with other emerging technologies such as microarrays and metagenomics.
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Affiliation(s)
- Marc G Dumont
- Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
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Schwartz MD, Obamwonyi AO, Thomas JD, Moorhead JF, Morgan BW. Acute methyl iodide exposure with delayed neuropsychiatric sequelae: report of a case. Am J Ind Med 2005; 47:550-6. [PMID: 15898088 DOI: 10.1002/ajim.20169] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Methyl iodide is a monohalomethane used as an analytic and organic chemistry reagent, as a methylating agent in organic chemical synthesis, and as a fumigant. In an acute exposure, methyl iodide is a pulmonary and dermal irritant. Chronic neurotoxicity has been reported in survivors of acute exposure. METHODS A review of the 11 case reports of methyl iodide poisoning in the medical literature of the 20th century found that six of the patients experienced a chronic neurological syndrome characterized primarily by delayed psychiatric, behavioral, and cognitive sequelae. RESULTS The case patient experienced a massive exposure to methyl iodide with resulting life-threatening burns. During convalescence, various cognitive and behavioral deficits became apparent. The results of a comprehensive evaluation at our occupational toxicology clinic, which included sequential neuropsychometric testing, are described. CONCLUSION The findings in the case patient may advance our understanding of the mechanisms and clinical manifestations of chronic neurotoxicity after exposure to methyl iodide.
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Affiliation(s)
- Michael D Schwartz
- Department of Emergency Medicine, Georgia Poison Center/Emory University, Atlanta, Georgia 30333, USA.
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40
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Abstract
Whereas most prokaryotes rely on binary fission for propagation, many species use alternative mechanisms, which include multiple offspring formation and budding, to reproduce. In some bacterial species, these eccentric reproductive strategies are essential for propagation, whereas in others the programmes are used conditionally. Although there are tantalizing images and morphological descriptions of these atypical developmental processes, none of these reproductive structures are characterized at the molecular genetic level. Now, with newly available analytical techniques, model systems to study these alternative reproductive programmes are being developed.
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Affiliation(s)
- Esther R Angert
- Department of Microbiology, Cornell University, 260A Wing Hall, Ithaca, New York 14853-5701, USA.
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Kalyuzhnaya MG, Lidstrom ME, Chistoserdova L. Utility of environmental primers targeting ancient enzymes: methylotroph detection in Lake Washington. MICROBIAL ECOLOGY 2004; 48:463-472. [PMID: 15696380 DOI: 10.1007/s00248-004-0212-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2003] [Accepted: 01/29/2004] [Indexed: 05/24/2023]
Abstract
Methods have been explored for detection of methylotrophs in natural samples, using environmental primers based on genes involved in the tetrahydromethanopterin (H4MPT)-linked C1 transfer pathway. The underlying hypotheses were that the H4MPT-linked pathway is an ancient methylotrophy pathway, based on gene divergence, and that primers targeting more divergent genes will detect a broader variety of methylotrophs compared to the variety uncovered using probes and primers targeting highly conserved genes. Three groups of novel primer sets were developed targeting mch, mtdB, and fae, key genes in the H4MPT-linked pathway, and these were used to assess the variety of microorganisms possessing these genes in sediments from Lake Washington in Seattle, WA. Environmental clone libraries were constructed for each of the genes and were analyzed by RFLP, and representatives of different RFLP groups were sequenced and subjected to phylogenetic analysis. A combination of all three sets of novel primers allowed detection of the two previously characterized groups of methylotrophs in the site: methanotrophs of the (alpha- and the gamma-proteobacterial groups, belonghg to genera Methylosinus, Methylocystis, Methylomonas, Methylobacter, Methylomicrobium, and Methylococcus. In addition to the genes belonging to known methanotroph populations, novel genes were identified, suggesting existence of previously undetected microbial groups possessing C1 transfer functions in this site. These included sequences clustering with the well-characterized methylotrophic phyla, Methylobacterium, Hyphomicrobium, and Xanthobacter. In addition, sequences divergent from those known for any groups of methylotrophs or methanogens were obtained, suggesting the presence of a yet unidentified microbial group possessing this H4MPT-linked C1 transfer pathway.
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Affiliation(s)
- M G Kalyuzhnaya
- Department of Chemical Engineering, University of Washington, Seattle, WA 98195-2180, USA
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Barlaz MA, Green RB, Chanton JP, Goldsmith CD, Hater GR. Evaluation of a biologically active cover for mitigation of landfill gas emissions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2004; 38:4891-4899. [PMID: 15487801 DOI: 10.1021/es049605b] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Landfills are the third largest source of anthropogenic CH4 in the United States, and there is potential for reduction in this source of greenhouse gases and other contaminants. The objective of this work was to contrast emissions of CH4 and non-methane organic compounds (NMOCs) from landfill cells covered with soil or a biologically active cover consisting of yard waste compost. On the basis of four field campaigns over 14 months, CH4 emissions from the biocover (BC) varied from -1.73 to 1.33 g m(-2) d(-1), with atmospheric uptake measured in 52% of tests. BC emissions did not increase when the gas collection system was turned off. Uptake of atmospheric CH4 was measured in 54% of tests on the soil cover (SC) when the gas collection was system active and 12% when the gas collection system was off. Many (26%) relatively high fluxes (>15 g m(-2) d(-1)) were measured from the SC as were some dramatic effects due to deactivation of the gas collection system. In tests with positive emissions, stable isotope measurements showed that the BC and SC were responsible for oxidation of 55% and 21% of the CH4 reaching the bottom of the respective cover. Seven of the highest 10 NMOC emissions were measured in the SC, and 17 of 21 fluxes for speciated organic compounds were higher in the SC. The relationship between CH4, NMOC, and individual organic compound emissions suggested a correlation between CH4 and trace organic oxidation. BCs can reduce landfill gas emissions in the absence of a gas collection system and can serve as a polishing step in the presence of an active system.
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Affiliation(s)
- M A Barlaz
- Department of Civil, Construction, and Environmental Engineering, Box 7908, North Carolina State University, Raleigh, North Carolina 27695-7908, USA.
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Borodina E, McDonald IR, Murrell JC. Chloromethane-dependent expression of the cmu gene cluster of Hyphomicrobium chloromethanicum. Appl Environ Microbiol 2004; 70:4177-86. [PMID: 15240299 PMCID: PMC444766 DOI: 10.1128/aem.70.7.4177-4186.2004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2004] [Accepted: 03/24/2004] [Indexed: 11/20/2022] Open
Abstract
The methylotrophic bacterium Hyphomicrobium chloromethanicum CM2 can utilize chloromethane (CH(3)Cl) as the sole carbon and energy source. Previously genes cmuB, cmuC, cmuA, and folD were shown to be essential for the growth of Methylobacterium chloromethanicum on CH(3)Cl. These CH(3)Cl-specific genes were subsequently detected in H. chloromethanicum. Transposon and marker exchange mutagenesis studies were carried out to identify the genes essential for CH(3)Cl metabolism in H. chloromethanicum. New developments in genetic manipulation of Hyphomicrobium are presented in this study. An electroporation protocol has been optimized and successfully applied for transformation of mutagenesis plasmids into H. chloromethanicum to generate stable CH(3)Cl-negative mutants. Both transposon and marker exchange mutageneses were highly applicable for genetic analysis of Hyphomicrobium. A reliable and reproducible selection procedure for screening of CH(3)Cl utilization-negative mutants has also been developed. Mutational inactivation of cmuB, cmuC, or hutI resulted in strains that were unable to utilize CH(3)Cl or to express the CH(3)Cl-dependent polypeptide CmuA. Reverse transcription-PCR analysis indicated that cmuB, cmuC, cmuA, fmdB, paaE, hutI, and metF formed a single cmuBCA-metF operon and were coregulated and coexpressed in H. chloromethanicum. This finding led to the conclusion that, in cmuB and cmuC mutants, impaired expression of cmuA was likely to be due to a polar effect of the defective gene (cmuB or cmuC) located upstream (5') of cmuA. The detrimental effect of mutation in hutI on the upstream (5')-located cmuA is not clear but indicated that all the genes located within the cmuBCA-metF operon are coordinately expressed. Expression of the cmuBCA-metF transcript was also shown to be strictly CH(3)Cl inducible and was not repressed by the alternative C(1) substrate methanol. Sequence analysis of a transposon mutant (D20) led to the discovery of the previously undetected hutI and metF genes located 3' of the paaE gene in H. chloromethanicum. MetF, a putative methylene-tetrahydrofolate reductase, had 27% identity to MetF from M. chloromethanicum. Mutational and transcriptional analysis data indicated that, in H. chloromethanicum, CH(3)Cl is metabolized via a corrinoid-specific (cmuA) and tetrahydrofolate-dependent (metF, purU, folD) methyltransfer system.
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Affiliation(s)
- Elena Borodina
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom.
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Wingenter OW, Haase KB, Strutton P, Friederich G, Meinardi S, Blake DR, Rowland FS. Changing concentrations of CO, CH(4), C(5)H(8), CH(3)Br, CH(3)I, and dimethyl sulfide during the Southern Ocean Iron Enrichment Experiments. Proc Natl Acad Sci U S A 2004; 101:8537-41. [PMID: 15173582 PMCID: PMC423229 DOI: 10.1073/pnas.0402744101] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Oceanic iron (Fe) fertilization experiments have advanced the understanding of how Fe regulates biological productivity and air-sea carbon dioxide (CO(2)) exchange. However, little is known about the production and consumption of halocarbons and other gases as a result of Fe addition. Besides metabolizing inorganic carbon, marine microorganisms produce and consume many other trace gases. Several of these gases, which individually impact global climate, stratospheric ozone concentration, or local photochemistry, have not been previously quantified during an Fe-enrichment experiment. We describe results for selected dissolved trace gases including methane (CH(4)), isoprene (C(5)H(8)), methyl bromide (CH(3)Br), dimethyl sulfide, and oxygen (O(2)), which increased subsequent to Fe fertilization, and the associated decreases in concentrations of carbon monoxide (CO), methyl iodide (CH(3)I), and CO(2) observed during the Southern Ocean Iron Enrichment Experiments.
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Affiliation(s)
- Oliver W Wingenter
- Department of Chemistry, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA.
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Abstract
The Escherichia coli AlkB protein is an iron- and 2-oxoglutarate-dependent oxygenase, repairing 1-methyladenine and 3-methylcytosine lesions in DNA. AlkB homologues are present in a number of bacterial species, and some bacteria have two different AlkB proteins. AlkB also repairs lesions in RNA, and the biological significance of RNA repair is discussed.
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Affiliation(s)
- Pål Ø Falnes
- Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, University of Oslo, Rikshospitalet, 0027 Oslo, Norway.
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Miller LG, Baesman SM, Oremland RS. Bioreactors for removing methyl bromide following contained fumigations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2003; 37:1698-1704. [PMID: 12731856 DOI: 10.1021/es026155j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Use of methyl bromide (MeBr) as a quarantine, commodity, or structural fumigant is under scrutiny because its release to the atmosphere contributes to the depletion of stratospheric ozone. A closed-system bioreactor consisting of 0.5 L of a growing culture of a previously described bacterium, strain IMB-1, removed MeBr (> 110 micromol L(-1)) from recirculating air. Strain IMB-1 grew slowly to high cell densities in the bioreactor using MeBr as its sole carbon and energy source. Bacterial oxidation of MeBr produced CO2 and hydrobromic acid (HBr), which required continuous neutralization with NaOH for the system to operate effectively. Strain IMB-1 was capable of sustained oxidation of large amounts of MeBr (170 mmol in 46 d). In an open-system bioreactor (10-L fermenter), strain IMB-1 oxidized a continuous supply of MeBr (220 /micromol L(-1) in air). Growth was continuous, and 0.5 mol of MeBr was removed from the air supply in 14 d. The specific rate of MeBr oxidation was 7 x 10(-16) mol cell(-1) h(-1). Bioreactors such as these can therefore be used to remove large quantities of contaminant MeBr, which opens the possibility of biodegradation as a practical means for its disposal.
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Affiliation(s)
- Laurence G Miller
- U.S. Geological Survey, Mail Stop 465, 345 Middlefield Road, Menlo Park, California 94025, USA.
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