1
|
Artuso I, Turrini P, Pirolo M, Lugli GA, Ventura M, Visca P. Phylogenomic Reconstruction and Metabolic Potential of the Genus Aminobacter. Microorganisms 2021; 9:1332. [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] [Grants] [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.
Collapse
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.)
| |
Collapse
|
2
|
Michener JK, Vuilleumier S, Bringel F, Marx CJ. Transfer of a Catabolic Pathway for Chloromethane in Methylobacterium Strains Highlights Different Limitations for Growth with Chloromethane or with Dichloromethane. Front Microbiol 2016; 7:1116. [PMID: 27486448 PMCID: PMC4949252 DOI: 10.3389/fmicb.2016.01116] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 07/04/2016] [Indexed: 11/14/2022] Open
Abstract
Chloromethane (CM) is an ozone-depleting gas, produced predominantly from natural sources, that provides an important carbon source for microbes capable of consuming it. CM catabolism has been difficult to study owing to the challenging genetics of its native microbial hosts. Since the pathways for CM catabolism show evidence of horizontal gene transfer, we reproduced this transfer process in the laboratory to generate new CM-catabolizing strains in tractable hosts. We demonstrate that six putative accessory genes improve CM catabolism, though heterologous expression of only one of the six is strictly necessary for growth on CM. In contrast to growth of Methylobacterium strains with the closely related compound dichloromethane (DCM), we find that chloride export does not limit growth on CM and, in general that the ability of a strain to grow on DCM is uncorrelated with its ability to grow on CM. This heterologous expression system allows us to investigate the components required for effective CM catabolism and the factors that limit effective catabolism after horizontal transfer.
Collapse
Affiliation(s)
- Joshua K Michener
- Department of Biological Engineering, Massachusetts Institute of TechnologyCambridge, MA, USA; Department of Organismic and Evolutionary Biology, Harvard UniversityCambridge, MA, USA; Biosciences Division, Oak Ridge National LaboratoryOak Ridge, TN, USA
| | | | | | - Christopher J Marx
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridge, MA, USA; Department of Biological Sciences, University of IdahoMoscow, ID, USA; Institute for Bioinformatics and Evolutionary Studies, University of IdahoMoscow, ID, USA; Center for Modeling Complex Interactions, University of IdahoMoscow, ID, USA
| |
Collapse
|
3
|
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]
|
4
|
Nadalig T, Greule M, Bringel F, Keppler F, Vuilleumier S. Probing the diversity of chloromethane-degrading bacteria by comparative genomics and isotopic fractionation. Front Microbiol 2014; 5:523. [PMID: 25360131 PMCID: PMC4197683 DOI: 10.3389/fmicb.2014.00523] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 09/19/2014] [Indexed: 11/13/2022] Open
Abstract
Chloromethane (CH3Cl) is produced on earth by a variety of abiotic and biological processes. It is the most important halogenated trace gas in the atmosphere, where it contributes to ozone destruction. Current estimates of the global CH3Cl budget are uncertain and suggest that microorganisms might play a more important role in degrading atmospheric CH3Cl than previously thought. Its degradation by bacteria has been demonstrated in marine, terrestrial, and phyllospheric environments. Improving our knowledge of these degradation processes and their magnitude is thus highly relevant for a better understanding of the global budget of CH3Cl. The cmu pathway, for chloromethane utilisation, is the only microbial pathway for CH3Cl degradation elucidated so far, and was characterized in detail in aerobic methylotrophic Alphaproteobacteria. Here, we reveal the potential of using a two-pronged approach involving a combination of comparative genomics and isotopic fractionation during CH3Cl degradation to newly address the question of the diversity of chloromethane-degrading bacteria in the environment. Analysis of available bacterial genome sequences reveals that several bacteria not yet known to degrade CH3Cl contain part or all of the complement of cmu genes required for CH3Cl degradation. These organisms, unlike bacteria shown to grow with CH3Cl using the cmu pathway, are obligate anaerobes. On the other hand, analysis of the complete genome of the chloromethane-degrading bacterium Leisingera methylohalidivorans MB2 showed that this bacterium does not contain cmu genes. Isotope fractionation experiments with L. methylohalidivorans MB2 suggest that the unknown pathway used by this bacterium for growth with CH3Cl can be differentiated from the cmu pathway. This result opens the prospect that contributions from bacteria with the cmu and Leisingera-type pathways to the atmospheric CH3Cl budget may be teased apart in the future.
Collapse
Affiliation(s)
- Thierry Nadalig
- Université de Strasbourg, Equipe Adaptations et Interactions Microbiennes dans l'Environnement, Unitès Mixtes de Recherche 7156 Centre National de la Recherche Scientifique, Génétique Moléculaire, Génomique, Microbiologie Strasbourg, France
| | - Markus Greule
- Institute of Earth Sciences, Ruprecht Karls University Heidelberg Heidelberg, Germany
| | - Françoise Bringel
- Université de Strasbourg, Equipe Adaptations et Interactions Microbiennes dans l'Environnement, Unitès Mixtes de Recherche 7156 Centre National de la Recherche Scientifique, Génétique Moléculaire, Génomique, Microbiologie Strasbourg, France
| | - Frank Keppler
- Institute of Earth Sciences, Ruprecht Karls University Heidelberg Heidelberg, Germany
| | - Stéphane Vuilleumier
- Université de Strasbourg, Equipe Adaptations et Interactions Microbiennes dans l'Environnement, Unitès Mixtes de Recherche 7156 Centre National de la Recherche Scientifique, Génétique Moléculaire, Génomique, Microbiologie Strasbourg, France
| |
Collapse
|
5
|
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]
|
6
|
Nadalig T, Farhan Ul Haque M, Roselli S, Schaller H, Bringel F, Vuilleumier S. Detection and isolation of chloromethane-degrading bacteria from the Arabidopsis thaliana phyllosphere, and characterization of chloromethane utilization genes. FEMS Microbiol Ecol 2011; 77:438-48. [PMID: 21545604 DOI: 10.1111/j.1574-6941.2011.01125.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Chloromethane gas is produced naturally in the phyllosphere, the compartment defined as the aboveground parts of vegetation, which hosts a rich bacterial flora. Chloromethane may serve as a growth substrate for specialized aerobic methylotrophic bacteria, which have been isolated from soil and water environments, and use cmu genes for chloromethane utilization. Evidence for the presence of chloromethane-degrading bacteria on the leaf surfaces of Arabidopsis thaliana was obtained by specific quantitative PCR of the cmuA gene encoding the two-domain methyltransferase corrinoid protein of chloromethane dehalogenase. Bacterial strains were isolated on a solid mineral medium with chloromethane as the sole carbon source from liquid mineral medium enrichment cultures inoculated with leaves of A. thaliana. Restriction analysis-based genotyping of cmuA PCR products was used to evaluate the diversity of chloromethane-degrading bacteria during enrichment and after strain isolation. The isolates obtained, affiliated to the genus Hyphomicrobium based on their 16S rRNA gene sequence and the presence of characteristic hyphae, dehalogenate chloromethane, and grow in a liquid culture with chloromethane as the sole carbon and energy source. The cmu genes of these isolates were analysed using new PCR primers, and their sequences were compared with those of previously reported aerobic chloromethane-degrading strains. The three isolates featured a colinear cmuBCA gene arrangement similar to that of all previously characterized strains, except Methylobacterium extorquens CM4 of known genome sequence.
Collapse
Affiliation(s)
- Thierry Nadalig
- Université de Strasbourg, UMR 7156 CNRS, Strasbourg, France.
| | | | | | | | | | | |
Collapse
|
7
|
Poretsky RS, Hewson I, Sun S, Allen AE, Zehr JP, Moran MA. Comparative day/night metatranscriptomic analysis of microbial communities in the North Pacific subtropical gyre. Environ Microbiol 2009; 11:1358-75. [PMID: 19207571 DOI: 10.1111/j.1462-2920.2008.01863.x] [Citation(s) in RCA: 239] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Metatranscriptomic analyses of microbial assemblages (< 5 microm) from surface water at the Hawaiian Ocean Time-Series (HOT) revealed community-wide metabolic activities and day/night patterns of differential gene expression. Pyrosequencing produced 75 558 putative mRNA reads from a day transcriptome and 75 946 from a night transcriptome. Taxonomic binning of annotated mRNAs indicated that Cyanobacteria contributed a greater percentage of the transcripts (54% of annotated sequences) than expected based on abundance (35% of cell counts and 21% 16S rRNA of libraries), and may represent the most actively transcribing cells in this surface ocean community in both the day and night. Major heterotrophic taxa contributing to the community transcriptome included alpha-Proteobacteria (19% of annotated sequences, most of which were SAR11-related) and gamma-Proteobacteria (4%). The composition of transcript pools was consistent with models of prokaryotic gene expression, including operon-based transcription patterns and an abundance of genes predicted to be highly expressed. Metabolic activities that are shared by many microbial taxa (e.g. glycolysis, citric acid cycle, amino acid biosynthesis and transcription and translation machinery) were well represented among the community transcripts. There was an overabundance of transcripts for photosynthesis, C1 metabolism and oxidative phosphorylation in the day compared with night, and evidence that energy acquisition is coordinated with solar radiation levels for both autotrophic and heterotrophic microbes. In contrast, housekeeping activities such as amino acid biosynthesis, membrane synthesis and repair, and vitamin biosynthesis were overrepresented in the night transcriptome. Direct sequencing of these environmental transcripts has provided detailed information on metabolic and biogeochemical responses of a microbial community to solar forcing.
Collapse
Affiliation(s)
- Rachel S Poretsky
- University of Georgia, Department of Marine Sciences, Athens, GA 30602, USA
| | | | | | | | | | | |
Collapse
|
8
|
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
| | | | | | | |
Collapse
|
9
|
Warner KL, Larkin MJ, Harper DB, Murrell JC, McDonald IR. Analysis of genes involved in methyl halide degradation in Aminobacter lissarensis CC495. FEMS Microbiol Lett 2006; 251:45-51. [PMID: 16102909 DOI: 10.1016/j.femsle.2005.07.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Revised: 07/17/2005] [Accepted: 07/19/2005] [Indexed: 11/29/2022] Open
Abstract
Aminobacter lissarensis CC495 is an aerobic facultative methylotroph capable of growth on glucose, glycerol, pyruvate and methylamine as well as the methyl halides methyl chloride and methyl bromide. Previously, cells grown on methyl chloride have been shown to express two polypeptides with apparent molecular masses of 67 and 29 kDa. The 67 kDa protein was purified and identified as a halomethane:bisulfide/halide ion methyltransferase. This study describes a single gene cluster in A. lissarensis CC495 containing the methyl halide utilisation genes cmuB, cmuA, cmuC, orf 188, paaE and hutI. The genes correspond to the same order and have a high similarity to a gene cluster found in Aminobacter ciceronei IMB-1 and Hyphomicrobium chloromethanicum strain CM2 indicating that genes encoding methyl halide degradation are highly conserved in these strains.
Collapse
Affiliation(s)
- Karen L Warner
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | | | | | | | | |
Collapse
|
10
|
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.
Collapse
Affiliation(s)
- Elena Borodina
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | | | | | | |
Collapse
|
11
|
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.
Collapse
Affiliation(s)
- Hendrik Schäfer
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, England, UK
| | | | | | | |
Collapse
|
12
|
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.
Collapse
Affiliation(s)
- Elena Borodina
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom.
| | | | | |
Collapse
|
13
|
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.
Collapse
Affiliation(s)
- Laurence G Miller
- U.S. Geological Survey, Mail Stop 465, 345 Middlefield Road, Menlo Park, California 94025, USA.
| | | | | |
Collapse
|
14
|
Studer A, McAnulla C, Büchele R, Leisinger T, Vuilleumier S. Chloromethane-induced genes define a third C1 utilization pathway in Methylobacterium chloromethanicum CM4. J Bacteriol 2002; 184:3476-84. [PMID: 12057941 PMCID: PMC135114 DOI: 10.1128/jb.184.13.3476-3484.2002] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2002] [Accepted: 03/27/2002] [Indexed: 11/20/2022] Open
Abstract
Methylobacterium chloromethanicum CM4 is an aerobic alpha-proteobacterium capable of growth with chloromethane as the sole carbon and energy source. Two proteins, CmuA and CmuB, were previously purified and shown to catalyze the dehalogenation of chloromethane and the vitamin B12-mediated transfer of the methyl group of chloromethane to tetrahydrofolate. Three genes located near cmuA and cmuB, designated metF, folD and purU and encoding homologs of methylene tetrahydrofolate (methylene-H4folate) reductase, methylene-H4folate dehydrogenase-methenyl-H4folate cyclohydrolase and formyl-H4folate hydrolase, respectively, suggested the existence of a chloromethane-specific oxidation pathway from methyl-tetrahydrofolate to formate in strain CM4. Hybridization and PCR analysis indicated that these genes were absent in Methylobacterium extorquens AM1, which is unable to grow with chloromethane. Studies with transcriptional xylE fusions demonstrated the chloromethane-dependent expression of these genes. Transcriptional start sites were mapped by primer extension and allowed to define three transcriptional units, each likely comprising several genes, that were specifically expressed during growth of strain CM4 with chloromethane. The DNA sequences of the deduced promoters display a high degree of sequence conservation but differ from the Methylobacterium promoters described thus far. As shown previously for purU, inactivation of the metF gene resulted in a CM4 mutant unable to grow with chloromethane. Methylene-H4folate reductase activity was detected in a cell extract of strain CM4 only in the presence of chloromethane but not in the metF mutant. Taken together, these data provide evidence that M. chloromethanicum CM4 requires a specific set of tetrahydrofolate-dependent enzymes for growth with chloromethane.
Collapse
Affiliation(s)
- Alex Studer
- Institut für Mikrobiologie, ETH Zürich, CH-8092 Zürich, Switzerland
| | | | | | | | | |
Collapse
|
15
|
McDonald IR, Warner KL, McAnulla C, Woodall CA, Oremland RS, Murrell JC. A review of bacterial methyl halide degradation: biochemistry, genetics and molecular ecology. Environ Microbiol 2002; 4:193-203. [PMID: 12010126 DOI: 10.1046/j.1462-2920.2002.00290.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Methyl halide-degrading bacteria are a diverse group of organisms that are found in both terrestrial and marine environments. They potentially play an important role in mitigating ozone depletion resulting from methyl chloride and methyl bromide emissions. The first step in the pathway(s) of methyl halide degradation involves a methyltransferase and, recently, the presence of this pathway has been studied in a number of bacteria. This paper reviews the biochemistry and genetics of methyl halide utilization in the aerobic bacteria Methylobacterium chloromethanicum CM4T, Hyphomicrobium chloromethanicum CM2T, Aminobacter strain IMB-1 and Aminobacter strain CC495. These bacteria are able to use methyl halides as a sole source of carbon and energy, are all members of the alpha-Proteobacteria and were isolated from a variety of polluted and pristine terrestrial environments. An understanding of the genetics of these bacteria identified a unique gene (cmuA) involved in the degradation of methyl halides, which codes for a protein (CmuA) with unique methyltransferase and corrinoid functions. This unique functional gene, cmuA, is being used to develop molecular ecology techniques to examine the diversity and distribution of methyl halide-utilizing bacteria in the environment and hopefully to understand their role in methyl halide degradation in different environments. These techniques will also enable the detection of potentially novel methyl halide-degrading bacteria.
Collapse
Affiliation(s)
- I R McDonald
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
| | | | | | | | | | | |
Collapse
|
16
|
Goodwin KD, Varner RK, Crill PM, Oremland RS. Consumption of tropospheric levels of methyl bromide by C(1) compound-utilizing bacteria and comparison to saturation kinetics. Appl Environ Microbiol 2001; 67:5437-43. [PMID: 11722890 PMCID: PMC93327 DOI: 10.1128/aem.67.12.5437-5443.2001] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pure cultures of methylotrophs and methanotrophs are known to oxidize methyl bromide (MeBr); however, their ability to oxidize tropospheric concentrations (parts per trillion by volume [pptv]) has not been tested. Methylotrophs and methanotrophs were able to consume MeBr provided at levels that mimicked the tropospheric mixing ratio of MeBr (12 pptv) at equilibrium with surface waters ( approximately 2 pM). Kinetic investigations using picomolar concentrations of MeBr in a continuously stirred tank reactor (CSTR) were performed using strain IMB-1 and Leisingeria methylohalidivorans strain MB2(T) - terrestrial and marine methylotrophs capable of halorespiration. First-order uptake of MeBr with no indication of threshold was observed for both strains. Strain MB2(T) displayed saturation kinetics in batch experiments using micromolar MeBr concentrations, with an apparent K(s) of 2.4 microM MeBr and a V(max) of 1.6 nmol h(-1) (10(6) cells)(-1). Apparent first-order degradation rate constants measured with the CSTR were consistent with kinetic parameters determined in batch experiments, which used 35- to 1 x 10(7)-fold-higher MeBr concentrations. Ruegeria algicola (a phylogenetic relative of strain MB2(T)), the common heterotrophs Escherichia coli and Bacillus pumilus, and a toluene oxidizer, Pseudomonas mendocina KR1, were also tested. These bacteria showed no significant consumption of 12 pptv MeBr; thus, the ability to consume ambient mixing ratios of MeBr was limited to C(1) compound-oxidizing bacteria in this study. Aerobic C(1) bacteria may provide model organisms for the biological oxidation of tropospheric MeBr in soils and waters.
Collapse
Affiliation(s)
- K D Goodwin
- Cooperative Institute for Marine and Atmospheric Studies, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida 33149, USA.
| | | | | | | |
Collapse
|
17
|
McAnulla C, McDonald IR, Murrell JC. Methyl chloride utilising bacteria are ubiquitous in the natural environment. FEMS Microbiol Lett 2001; 201:151-5. [PMID: 11470354 DOI: 10.1111/j.1574-6968.2001.tb10749.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Enrichment and isolation of methyl chloride utilising bacteria from a variety of pristine terrestrial, freshwater, estuarine and marine environments resulted in the detection of six new methyl chloride utilising Hyphomicrobium strains, strain CMC related to Aminobacter spp. and to two previously isolated methyl halide utilising bacteria CC495 and IMB-1, and a Gram-positive isolate SAC-4 phylogenetically related to Nocardioides spp. All the pristine environments sampled for enrichment resulted in the successful isolation of methyl chloride utilising organisms.
Collapse
Affiliation(s)
- C McAnulla
- Department of Biological Sciences, University of Warwick, CV4 7AL, Coventry, UK
| | | | | |
Collapse
|
18
|
Miller LG, Kalin RM, McCauley SE, Hamilton JT, Harper DB, Millet DB, Oremland RS, Goldstein AH. Large carbon isotope fractionation associated with oxidation of methyl halides by methylotrophic bacteria. Proc Natl Acad Sci U S A 2001; 98:5833-7. [PMID: 11344313 PMCID: PMC33299 DOI: 10.1073/pnas.101129798] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2000] [Accepted: 03/13/2001] [Indexed: 11/18/2022] Open
Abstract
The largest biological fractionations of stable carbon isotopes observed in nature occur during production of methane by methanogenic archaea. These fractionations result in substantial (as much as approximately 70 per thousand) shifts in delta(13)C relative to the initial substrate. We now report that a stable carbon isotopic fractionation of comparable magnitude (up to 70 per thousand) occurs during oxidation of methyl halides by methylotrophic bacteria. We have demonstrated biological fractionation with whole cells of three methylotrophs (strain IMB-1, strain CC495, and strain MB2) and, to a lesser extent, with the purified cobalamin-dependent methyltransferase enzyme obtained from strain CC495. Thus, the genetic similarities recently reported between methylotrophs, and methanogens with respect to their pathways for C(1)-unit metabolism are also reflected in the carbon isotopic fractionations achieved by these organisms. We found that only part of the observed fractionation of carbon isotopes could be accounted for by the activity of the corrinoid methyltransferase enzyme, suggesting fractionation by enzymes further along the degradation pathway. These observations are of potential biogeochemical significance in the application of stable carbon isotope ratios to constrain the tropospheric budgets for the ozone-depleting halocarbons, methyl bromide and methyl chloride.
Collapse
Affiliation(s)
- L G Miller
- United States Geological Survey, Menlo Park, CA 94025, USA.
| | | | | | | | | | | | | | | |
Collapse
|