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A M Happel - One of the best experts on this subject based on the ideXlab platform.
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aerobic biodegradation of methyl tert butyl ether by aquifer bacteria from leaking underground storage tank sites
Applied and Environmental Microbiology, 2001Co-Authors: Staci R. Kane, Tina C Legler, Holly C Pinkart, Carolyn Koester, Rolf U. Halden, Harry R Beller, A M HappelAbstract:The potential for aerobic methyl tert-butyl ether (MTBE) degradation was investigated with microcosms containing aquifer sediment and groundwater from four MTBE-contaminated sites characterized by oxygen-limited in situ conditions. MTBE depletion was observed for sediments from two sites (e.g., 4.5 mg/liter degraded in 15 days after a 4-day lag period), whereas no consumption of MTBE was observed for sediments from the other sites after 75 days. For sediments in which MTBE was consumed, 43 to 54% of added [U-14C]MTBE was mineralized to 14CO2. Molecular phylogenetic analyses of these sediments indicated the enrichment of species closely related to a known MTBE-degrading bacterium, strain PM1. At only one site, the presence of water-soluble gasoline components significantly inhibited MTBE degradation and led to a more pronounced accumulation of the metabolite tert-butyl alcohol. Overall, these results suggest that the effects of oxygen and water-soluble gasoline components on in situ MTBE degradation will vary from site to site and that phylogenetic analysis may be a promising predictor of MTBE biodegradation potential.
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aerobic biodegradation of methyl tert butyl ether by aquifer bacteria from leaking underground storage tank sites
Applied and Environmental Microbiology, 2001Co-Authors: Staci R. Kane, Tina C Legler, Holly C Pinkart, Carolyn Koester, Rolf U. Halden, Harry R Beller, A M HappelAbstract:The potential for aerobic methyl tert-butyl ether (MTBE) degradation was investigated with microcosms containing aquifer sediment and groundwater from four MTBE-contaminated sites characterized by oxygen-limited in situ conditions. MTBE depletion was observed for sediments from two sites (e.g., 4.5 mg/liter degraded in 15 days after a 4-day lag period), whereas no consumption of MTBE was observed for sediments from the other sites after 75 days. For sediments in which MTBE was consumed, 43 to 54% of added [U-14C]MTBE was mineralized to 14CO2. Molecular phylogenetic analyses of these sediments indicated the enrichment of species closely related to a known MTBE-degrading bacterium, strain PM1. At only one site, the presence of water-soluble gasoline components significantly inhibited MTBE degradation and led to a more pronounced accumulation of the metabolite tert-butyl alcohol. Overall, these results suggest that the effects of oxygen and water-soluble gasoline components on in situ MTBE degradation will vary from site to site and that phylogenetic analysis may be a promising predictor of MTBE biodegradation potential.
Kate M. Scow - One of the best experts on this subject based on the ideXlab platform.
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AND GROUNDWATER ENVIRONMENTS Research Category: Category III Water Quality: wastewater treatment and reclamation processes Principal Investigator:
2015Co-Authors: Kate M. Scow, Associate ProfessorAbstract:The fuel additive, methyl tertiary-butyl ether (MTBE), has become a widespread environmental contaminant in the past decade. Since MTBE was introduced to gasoline as an additive in 1988, its production has increased to 17 billion pounds per year and currently comprises up to 15 % of some reformulated gasoline (Kirshner, 1995). This increased usage coupled with high incidences of leaking underground storage tanks has led to MTBE contamination of groundwater, soils and sediments. There is little evidence that extensive intrinsic remediation is occurring at MTBE contaminated sites. Thus it is important to explore the potential of using active bioremediation, a potentially promising technology for inexpensive treatment of MTBE contaminated groundwater. Many challenges must be overcome before bioremediation of MTBE can be successfully implemented at the field scale. Challenges include the identification and culturing of an MTBE-degrading inoculant, the engineering constraints associated with in situ remediation, and insurance of inoculant survival and activity in contaminated environments. Our laboratory has recently isolated a bacterial culture, Strain PM 1, which is capable of using MTBE as its sole carbon and energy source at relatively rapid rates. I
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naturally occurring bacteria similar to the methyl tert butyl ether MTBE degrading strain pm1 are present in MTBE contaminated groundwater
Applied and Environmental Microbiology, 2003Co-Authors: Krassimira R Hristova, Binyam Gebreyesus, Douglas M Mackay, Kate M. ScowAbstract:Methyl tert-butyl ether (MTBE) is a widespread groundwater contaminant that does not respond well to conventional treatment technologies. Growing evidence indicates that microbial communities indigenous to groundwater can degrade MTBE under aerobic and anaerobic conditions. Although pure cultures of microorganisms able to degrade or cometabolize MTBE have been reported, to date the specific organisms responsible for MTBE degradation in various field studies have not be identified. We report that DNA sequences almost identical (99% homology) to those of strain PM1, originally isolated from a biofilter in southern California, are naturally occurring in an MTBE-polluted aquifer in Vandenberg Air Force Base (VAFB), Lompoc, California. Cell densities of native PM1 (measured by TaqMan quantitative PCR) in VAFB groundwater samples ranged from below the detection limit (in anaerobic sites) to 103 to 104 cells/ml (in oxygen-amended sites). In groundwater from anaerobic or aerobic sites incubated in microcosms spiked with 10 μg of MTBE/liter, densities of native PM1 increased to approximately 105 cells/ml. Native PM1 densities also increased during incubation of VAFB sediments during MTBE degradation. In controlled field plots amended with oxygen, artificially increasing the MTBE concentration was followed by an increase in the in situ native PM1 cell density. This is the first reported relationship between in situ MTBE biodegradation and densities of MTBE-degrading bacteria by quantitative molecular methods.
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in situ MTBE biodegradation supported by diffusive oxygen release
Environmental Science & Technology, 2002Co-Authors: Ryan D Wilson, Douglas M Mackay, Kate M. ScowAbstract:Microcosm studies with sediments from Vandenberg Air Force Base, CA, suggest that native aerobic methyl tert-butyl ether (MTBE)-degrading microorganisms can be stimulated to degrade MTBE. In a series of field experiments, dissolved oxygen has been released into the anaerobic MTBE plume by diffusion through the walls of oxygen-pressurized polymeric tubing placed in contact with the flowing groundwater. MTBE concentrations were decreased from several hundred to less than 10 μg/L during passage through the induced aerobic zone, due apparently to in situ biodegradation: abiotic MTBE loss mechanisms were insignificant. Lag time for initiation of degradation was less than 2 months, and the apparent pseudo-first-order degradation rate was 5.3 day-1. Additional MTBE was added in steps to raise the influent concentration to a maximum of 2.1 mg/L. With each step, MTBE was degraded within the preestablished aerobic treatment zone at rates ranging from 4.4 to 8.6 day-1. Excess dissolved oxygen suggested that even hi...
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Aerobic MTBE biodegradation: an examination of past studies, current challenges and future research directions
Biodegradation, 2000Co-Authors: Rula A. Deeb, Kate M. Scow, Lisa Alvarez-cohenAbstract:With the current practice of amending gasoline with up to 15% by volume MTBE, the contamination of groundwater by MTBE has become widespread. As a result, the bioremediation of MTBE-impacted aquifers has become an active area of research. A review of the current literature on the aerobic biodegradation of MTBE reveals that a number of cultures from diverse environments can either partially degrade or completely mineralize MTBE. MTBE is either utilized as a sole carbon and energy source or is degraded cometabolically by cultures grown on alkanes. Reported degradation rates range from 0.3 to 50 mg MTBE/g cells/h while growth rates (0.01–0.05 g MTBE/g cells/d) and cellular yields (0.1–0.2 g cells/g MTBE) are generally low. Studies on the mechanisms of MTBE degradation indicate that a monooxygenase enzyme cleaves the ether bond yielding tert -butyl alcohol (TBA) and formaldehyde as the dominant detectable intermediates. TBA is further degraded to 2-methyl-2-hydroxy-1-propanol, 2-hydroxyisobutyric acid, 2-propanol, acetone, hydroxyacteone and eventually, carbon dioxide. The majority of these intermediates are also common to mammalian MTBE metabolism. Laboratory studies on the degradation of MTBE in the presence of gasoline aromatics reveal that while degradation rates of other gasoline components are generally not inhibited by MTBE, MTBE degradation could be inhibited in the presence of more easily biodegradable compounds. Controlled field studies are clearly needed to elucidate MTBE degradation potential in co-contaminant plumes. Based on the reviewed studies, it is likely that a bioremediation strategy involving direct metabolism, cometabolism, bioaugmentation, or some combination thereof, could be applied as a feasible and cost-effective treatment method for MTBE contamination.
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biodegradation of methyl tert butyl ether by a bacterial pure culture
Applied and Environmental Microbiology, 1999Co-Authors: Jessica R Hanson, Corinne E Ackerman, Kate M. ScowAbstract:Since its initial use as a gasoline oxygenate in the 1980s, methyl tert-butyl ether (MTBE) production has risen to 7.7 billion kilograms per year and currently comprises up to 15% (vol/vol) of some reformulated gasolines (9). This increased usage coupled with high incidences of leaking underground storage tanks and recreational watercraft operation has led to MTBE contamination of surface waters, groundwater, soils, and sediments. The compound is extremely water soluble and moderately volatile; thus, it is highly mobile in both groundwater and surface waters and can volatilize to contaminate the vadose zone, surface soils, and sediments. Currently, the U.S. Environmental Protection Agency (EPA) lists MTBE as a possible carcinogen; however, toxicity limits are a subject of debate. Since MTBE can be detected by both taste and odor at concentrations as low as 35 μg liter−1, the EPA has recommended keeping concentrations in drinking water below a nuisance limit of 40 μg liter−1 (1). Unlike other gasoline components, including benzene (14, 16) and toluene (6, 14), there are few reports of microorganisms in either pure or mixed cultures capable of biodegrading MTBE. Salanitro et al. were the first to report the bacterial degradation of MTBE (17). In that study, a mixed microbial consortium was found to degrade 120 μg of MTBE ml−1 at a rate of 34 mg g of cells−1 h−1. The metabolic intermediate tert-butyl alcohol (TBA) was observed; however, further analysis of the metabolic pathway was complicated by the presence of more than one bacterial species in the degrading culture. Eweis et al. have reported the enrichment of a second microbial consortium capable of degrading MTBE (3). In that study, a mixed bacterial culture was obtained by subculturing the solid support material from a compost biofilter located at the Los Angeles County Joint Water Pollution Control Plant (Carson, Calif.) that began removing MTBE after a 1-year acclimation period. The microbial consortium was used to inoculate a bench-scale biofilter established for treatment of MTBE-contaminated airstreams (4). The compost-derived consortium was the source of the bacterial isolate described in our study. To date, there has been a single study describing pure bacterial cultures capable of using MTBE as a sole carbon and energy source. Mo et al. described three bacterial strains (an Arthrobacter, a Rhodococcus, and a Methylobacterium strain) that degraded up to 29% of an initial concentration of 200 μg of MTBE ml−1 in 2 weeks; however, complete MTBE degradation by these cultures was not observed (11). In cometabolism experiments researchers have reported that propane-enriched environmental isolates are capable of mineralizing MTBE, but these organisms cannot grow on MTBE without prior induction by another compound (20). There is also one report of a strain of the fungal genus Graphium capable of cometabolizing MTBE in the presence of n-butane (7). Several studies have investigated the potential for natural attenuation of MTBE in soils and sediment. Yeh and Novak measured the anaerobic biodegradation of MTBE in soil microcosms and found that MTBE was degraded only in the low organic matter soils (22). Mormille et al. (12) detected anaerobic degradation of MTBE in one replicate of a fuel-contaminated river sediment after a 152-day acclimation period. Most recently, Bradley et al. (2) have reported mineralization of both MTBE and TBA in streambed sediments under aerobic conditions. In addition to soil and sediment studies, the potential for natural attenuation of MTBE has been evaluated through modeling studies, for example, in the Borden aquifer (19). Laboratory confirmation of biodegradation potential in samples from sites where natural attenuation has been hypothesized is not part of these studies. Given the increasing incidence of MTBE in the environment and the apparently low rates of MTBE natural attenuation, it is important to find bacterial cultures capable of rapid MTBE degradation and survival outside of the laboratory. Our objectives in this study were to isolate and characterize a bacterial culture capable of using MTBE as its sole carbon and energy source. We then evaluated this organism, designated strain PM1, for the ability to degrade MTBE when inoculated into groundwater core material. Our results indicate that strain PM1 may be effective for use in the bioaugmentation of MTBE-contaminated environments.
Staci R. Kane - One of the best experts on this subject based on the ideXlab platform.
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aerobic biodegradation of methyl tert butyl ether by aquifer bacteria from leaking underground storage tank sites
Applied and Environmental Microbiology, 2001Co-Authors: Staci R. Kane, Tina C Legler, Holly C Pinkart, Carolyn Koester, Rolf U. Halden, Harry R Beller, A M HappelAbstract:The potential for aerobic methyl tert-butyl ether (MTBE) degradation was investigated with microcosms containing aquifer sediment and groundwater from four MTBE-contaminated sites characterized by oxygen-limited in situ conditions. MTBE depletion was observed for sediments from two sites (e.g., 4.5 mg/liter degraded in 15 days after a 4-day lag period), whereas no consumption of MTBE was observed for sediments from the other sites after 75 days. For sediments in which MTBE was consumed, 43 to 54% of added [U-14C]MTBE was mineralized to 14CO2. Molecular phylogenetic analyses of these sediments indicated the enrichment of species closely related to a known MTBE-degrading bacterium, strain PM1. At only one site, the presence of water-soluble gasoline components significantly inhibited MTBE degradation and led to a more pronounced accumulation of the metabolite tert-butyl alcohol. Overall, these results suggest that the effects of oxygen and water-soluble gasoline components on in situ MTBE degradation will vary from site to site and that phylogenetic analysis may be a promising predictor of MTBE biodegradation potential.
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aerobic biodegradation of methyl tert butyl ether by aquifer bacteria from leaking underground storage tank sites
Applied and Environmental Microbiology, 2001Co-Authors: Staci R. Kane, Tina C Legler, Holly C Pinkart, Carolyn Koester, Rolf U. Halden, Harry R Beller, A M HappelAbstract:The potential for aerobic methyl tert-butyl ether (MTBE) degradation was investigated with microcosms containing aquifer sediment and groundwater from four MTBE-contaminated sites characterized by oxygen-limited in situ conditions. MTBE depletion was observed for sediments from two sites (e.g., 4.5 mg/liter degraded in 15 days after a 4-day lag period), whereas no consumption of MTBE was observed for sediments from the other sites after 75 days. For sediments in which MTBE was consumed, 43 to 54% of added [U-14C]MTBE was mineralized to 14CO2. Molecular phylogenetic analyses of these sediments indicated the enrichment of species closely related to a known MTBE-degrading bacterium, strain PM1. At only one site, the presence of water-soluble gasoline components significantly inhibited MTBE degradation and led to a more pronounced accumulation of the metabolite tert-butyl alcohol. Overall, these results suggest that the effects of oxygen and water-soluble gasoline components on in situ MTBE degradation will vary from site to site and that phylogenetic analysis may be a promising predictor of MTBE biodegradation potential.
Jan Gerritse - One of the best experts on this subject based on the ideXlab platform.
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Ethyl tert-butyl ether (EtBE) degradation by an algal-bacterial culture obtained from contaminated groundwater
Water Research, 2019Co-Authors: Marcelle J. Van Der Waals, Caroline Plugge, Marion Meima-franke, Pieter De Waard, Paul L. E. Bodelier, Hauke Smidt, Jan GerritseAbstract:EtBE is a fuel oxygenate that is synthesized from (bio)ethanol and fossil-based isobutylene, and replaces the fossil-based MTBE. Biodegradation of EtBE to harmless metabolites or end products can reduce the environmental and human health risks after accidental release. In this study, an algal-bacterial culture enriched from contaminated groundwater was used to (i) assess the potential for EtBE degradation, (ii) resolve the EtBE degradation pathway and (iii) characterize the phylogenetic composition of the bacterial community involved in EtBE degradation in contaminated groundwater. In an unamended microcosm, algal growth was observed after eight weeks when exposed to a day-night light cycle. In the fed-batch reactor, oxygen produced by the algae Scenedesmus and Chlorella was used by bacteria to degrade 50 μM EtBE replenishments with a cumulative total of 1250 μM in a day/night cycle (650 lux), over a period of 913 days. The microbial community in the fed-batch reactor degraded EtBE, using a P450 monooxygenase and 2-hydroxyisobutyryl-CoA mutase, to tert-butyl alcohol (TBA), ethanol and CO2 as determined using 13C nuclear magnetic resonance spectroscopy (NMR) and gas chromatography. Stable isotope probing (SIP) with 13C6 labeled EtBE in a fed-batch vessel showed no significant difference in community profiles of the 13C and 12C enriched DNA fractions, with representatives of the families Halomonadaceae, Shewanellaceae, Rhodocyclaceae, Oxalobacteraceae, Comamonadaceae, Sphingomonadaceae, Hyphomicrobiaceae, Candidatus Moranbacteria, Omnitrophica, Anaerolineaceae, Nocardiaceae, and Blastocatellaceae. This is the first study describing micro-oxic degradation of EtBE by an algal-bacterial culture. This algal-bacterial culture has advantages compared with conventional aerobic treatments: (i) a lower risk of EtBE evaporation and (ii) no need for external oxygen supply in the presence of light. This study provides novel leads towards future possibilities to implement algal-bacterial consortia in field-scale groundwater or wastewater treatment.
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ethyl tert butyl ether etbe degradation by an algal bacterial culture
2018Co-Authors: J M Van Der Waals, Caroline Plugge, Pieter De Waard, Paul L. E. Bodelier, Hauke Smidt, Marion Meimafranke, Jan GerritseAbstract:EtBE is a fuel oxygenate, made out of (bio)ethanol replacing MTBE. Biodegradation of EtBE can reduce the risk after accidental release in the environment. The oxygen produced by Scenedesmus and Chlorella was used by microorganisms to degrade EtBE using a P450 monooxygenase cytochrome. Metabolites formed during the micro-oxic EtBE degradation were tert-butyl alcohol (TBA), ethanol and CO2 determined using 13C nuclear magnetic resonance spectroscopy (NMR) and gas chromatography. Stable isotope probing (SIP) of the 13C and 12C enriched EtBE fractions showed no significant difference between phylotypes, including Halomonadaceae, Shewanellaceae, Rhodocyclaceae, Oxalobacteraceae, Comamonadaceae, Sphingomonadaceae, Hyphomicrobiaceae, Candidatus Moranbacteria, Omnitrophica, Anaerolineaceae, Nocardiaceae, and Blastocatellaceae. This study is the first study describing micro-oxic degradation of EtBE by an algal-bacterial culture.
Michael R Hyman - One of the best experts on this subject based on the ideXlab platform.
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oxidation of gasoline oxygenates by closely related non haem iron alkane hydroxylases in pseudomonas mendocina kr1 and other n octane utilizing pseudomonas strains
Environmental Microbiology Reports, 2010Co-Authors: Christy A Smith, Michael R HymanAbstract:Pseudomonas mendocina KR1 oxidizes the gasoline oxygenate methyl tertiary butyl ether (MTBE) to tertiary butyl alcohol (TBA) during growth on C5 -C8 n-alkanes. We have further explored oxidation of ether oxygenates by this strain to help identify the enzyme that catalyses these reactions. High levels of MTBE-oxidizing activity occurred in resting cells grown on C5 -C8 n-alkanes. Lower activities occurred in cells grown on longer-chain n-alkanes (C9 -C11 ) and 1°-alcohols (C5 -C10 ). N-octane-grown cells also oxidized tertiary amyl methyl ether (TAME) to tertiary amyl alcohol (TAA), but did not oxidize ethyl tertiary butyl ether (ETBE), TBA or TAA. A 39 kDa polypeptide in whole cell extracts of n-octane-grown cells strongly cross-reacted with an anti-AlkB polyclonal antiserum in an SDS-PAGE/immunoblot. This polypeptide was absent or less abundant in cells grown on dextrose, dextrose plus dicyclopropylketone or 1-octanol. N-octane-grown cells of Pseudomonas aeruginosa strains KSLA-473 and ATCC 17423 oxidized MTBE and TAME but not ETBE. N-hexadecane-grown cells of these strains and strain PAO1 did not oxidize any of the oxygenates tested. Our results indicate ether oxygenate-degrading activity in alkane-utilizing pseudomonads is consistently observed with close homologues of the GPo1 non-haem-iron alkane hydroxylases but is otherwise not a consistent catalytic feature of these diverse enzymes.
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cometabolism of methyl tertiary butyl ether and gaseous n alkanes by pseudomonas mendocina kr 1 grown on c5 to c8 n alkanes
Applied and Environmental Microbiology, 2003Co-Authors: Christy A Smith, Kirk T Oreilly, Michael R HymanAbstract:Pseudomonas mendocina KR-1 grew well on toluene, n-alkanes (C5 to C8), and 1 degrees alcohols (C2 to C8) but not on other aromatics, gaseous n-alkanes (C1 to C4), isoalkanes (C4 to C6), 2 degrees alcohols (C3 to C8), methyl tertiary butyl ether (MTBE), or tertiary butyl alcohol (TBA). Cells grown under carbon-limited conditions on n-alkanes in the presence of MTBE (42 micromoles) oxidized up to 94% of the added MTBE to TBA. Less than 3% of the added MTBE was oxidized to TBA when cells were grown on either 1 degrees alcohols, toluene, or dextrose in the presence of MTBE. Concentrated n-pentane-grown cells oxidized MTBE to TBA without a lag phase and without generating tertiary butyl formate (TBF) as an intermediate. Neither TBF nor TBA was consumed by n-pentane-grown cells, while formaldehyde, the expected C1 product of MTBE dealkylation, was rapidly consumed. Similar Ks values for MTBE were observed for cells grown on C5 to C8 n-alkanes (12.95 +/- 2.04 mM), suggesting that the same enzyme oxidizes MTBE in cells grown on each n-alkane. All growth-supporting n-alkanes (C5 to C8) inhibited MTBE oxidation by resting n-pentane-grown cells. Propane (Ki = 53 micromoles) and n-butane (Ki = 16 micromoles) also inhibited MTBE oxidation, and both gases were also consumed by cells during growth on n-pentane. Cultures grown on C5 to C8 n-alkanes also exhibited up to twofold-higher levels of growth in the presence of propane or n-butane, whereas no growth stimulation was observed with methane, ethane, MTBE, TBA, or formaldehyde. The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism.
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characterization of the initial reactions during the cometabolic oxidation of methyl tert butyl ether by propane grown mycobacterium vaccae job5
Applied and Environmental Microbiology, 2003Co-Authors: Christy A Smith, Kirk T Oreilly, Michael R HymanAbstract:The initial reactions in the cometabolic oxidation of the gasoline oxygenate, methyl tert-butyl ether (MTBE), by Mycobacterium vaccae JOB5 have been characterized. Two products, tert-butyl formate (TBF) and tert-butyl alcohol (TBA), rapidly accumulated extracellularly when propane-grown cells were incubated with MTBE. Lower rates of TBF and TBA production from MTBE were also observed with cells grown on 1- or 2-propanol, while neither product was generated from MTBE by cells grown on casein-yeast extract-dextrose broth. Kinetic studies with propane-grown cells demonstrated that TBF is the dominant (≥80%) initial product of MTBE oxidation and that TBA accumulates from further biotic and abiotic hydrolysis of TBF. Our results suggest that the biotic hydrolysis of TBF is catalyzed by a heat-stable esterase with activity toward several other tert-butyl esters. Propane-grown cells also oxidized TBA, but no further oxidation products were detected. Like the oxidation of MTBE, TBA oxidation was fully inhibited by acetylene, an inactivator of short-chain alkane monooxygenase in M. vaccae JOB5. Oxidation of both MTBE and TBA was also inhibited by propane (Ki = 3.3 to 4.4 μM). Values for Ks of 1.36 and 1.18 mM and for Vmax of 24.4 and 10.4 nmol min−1 mg of protein−1 were derived for MTBE and TBA, respectively. We conclude that the initial steps in the pathway of MTBE oxidation by M. vaccae JOB5 involve two reactions catalyzed by the same monooxygenase (MTBE and TBA oxidation) that are temporally separated by an esterase-catalyzed hydrolysis of TBF to TBA. These results that suggest the initial reactions in MTBE oxidation by M. vaccae JOB5 are the same as those that we have previously characterized in gaseous alkane-utilizing fungi.
