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Environmental Science & Technology May 2019Spatially resolved emission inventories were used with an atmospheric dispersion model to predict ambient concentrations of methane, ethane, and propane in the Eagle...
Spatially resolved emission inventories were used with an atmospheric dispersion model to predict ambient concentrations of methane, ethane, and propane in the Eagle Ford oil and gas production region in south central Texas; predicted concentrations were compared to ground level observations. Using a base case inventory, predicted median propane/ethane concentration ratios were 106% higher (95% CI: 83% higher-226% higher) than observations, while median ethane/methane concentration ratios were 112% higher (95% CI: 17% higher-228% higher) than observations. Predicted median propane and ethane concentrations were factors of 6.9 (95% CI: 3-15.2) and 3.4 (95% CI: 1.4-9) larger than observations, respectively. Predicted median methane concentrations were 7% higher (95% CI: 39% lower-37% higher) than observations. These comparisons indicate that sources of emissions with high propane/ethane ratios (condensate tank flashing) were likely overestimated in the inventories. Because sources of propane and ethane emissions are also sources of methane emissions, the results also suggest that sources of emissions with low ethane/methane ratios (midstream sources) were underestimated. This analysis demonstrates the value of using multiple light alkanes in attributing sources of methane emissions and evaluating the performance of methane emission inventories for oil and natural gas production regions.
Topics: Air Pollutants; Alkanes; Ethane; Methane; Natural Gas; Texas
PubMed: 30912428
DOI: 10.1021/acs.est.8b05828 -
Chemistry & Biodiversity May 2023n-Alkane and long-chain alcohol (LCOH) profiles of needle cuticular waxes of nine provenances of three Pinus species (P. taeda. P. pinaster and P. pinea) were determined...
n-Alkane and long-chain alcohol (LCOH) profiles of needle cuticular waxes of nine provenances of three Pinus species (P. taeda. P. pinaster and P. pinea) were determined and their chemotaxonomic importance was studied. n-Alkanes concentrations were very low in all Pinus spp. A lack of ability of these compounds to differentiate Pinus spp. and their provenances was observed. LCOH concentrations were much higher, being nonacosan-10-ol (10-C -OH) the most abundant one in all Pinus spp. Total LCOH concentrations varied (P<0.001) between Pinus spp. with P. taeda presenting the highest (P<0.05) value and P. pinea the lowest one. Differences in LCOH profiles were large (P<0.001) and allowed separation of Pinus spp. in the Principal Component Analysis (PCA). Although a noticeable separation of individuals was not observed. cluster analysis on LCOH concentrations allowed a clear distinction between species, indicating their potential to be used as chemotaxonomic markers to differentiate provenances of different Pinus spp.
Topics: Alkanes; Gas Chromatography-Mass Spectrometry; Pinus; Waxes; Ethanol
PubMed: 37066849
DOI: 10.1002/cbdv.202300043 -
Environmental Microbiology Apr 2019Anaerobic oxidation of methane greatly contributes to global carbon cycling, yet the anaerobic oxidation of non-methane alkanes by archaea was only recently detected in...
Anaerobic oxidation of methane greatly contributes to global carbon cycling, yet the anaerobic oxidation of non-methane alkanes by archaea was only recently detected in lab enrichments. The distribution and activity of these archaea in natural environments are not yet reported and understood. Here, a combination of metagenomic and metatranscriptomic approaches was utilized to understand the ecological roles and metabolic potentials of methyl-coenzyme M reductase (MCR)-based alkane oxidizing (MAO) archaea in Guaymas Basin sediments. Diverse MAO archaea, including multi-carbon alkane oxidizer Ca. Syntrophoarchaeum spp., anaerobic methane oxidizing archaea ANME-1 and ANME-2c as well as sulfate-reducing bacteria HotSeep-1 and Seep-SRB2 that potentially involved in MAO processes, coexisted and showed activity in Guaymas Basin sediments. High-quality genomic bins of Ca. Syntrophoarchaeum spp., ANME-1 and ANME-2c were retrieved. They all contain and expressed mcr genes and genes in Wood-Ljungdahl pathway for the complete oxidation from alkane to CO in local environment, while Ca. Syntrophoarchaeum spp. also possess beta-oxidation genes for multi-carbon alkane degradation. A global survey of potential multi-carbon alkane metabolism archaea shows that they are usually present in organic rich environments but are not limit to hydrothermal or marine ecosystems. Our study provided new insights into ecological and metabolic potentials of MAO archaea in natural environments.
Topics: Alkanes; Anaerobiosis; Archaea; Carbon; Ecosystem; Genes, Archaeal; Geologic Sediments; Hydrothermal Vents; Metagenome; Methane; Oxidation-Reduction; Phylogeny
PubMed: 30790413
DOI: 10.1111/1462-2920.14568 -
Extremophiles : Life Under Extreme... Jul 2020The mineralization of alkane is mainly driven by microorganisms, and the detailed mechanisms of long-chain aliphatic alkane degradation are undeciphered in archaea. We...
The mineralization of alkane is mainly driven by microorganisms, and the detailed mechanisms of long-chain aliphatic alkane degradation are undeciphered in archaea. We used a hexadecane-degrading haloarchaeon, Halorientalis hydrocarbonoclasticus IM1011 (= CGMCC 13754), as a model system to decode this through transcriptomic and biochemical studies. During growth on hexadecane as sole carbon source, the activity of 3-hydroxyacyl-CoA dehydrogenase, a β-oxidation pathway enzyme, was measured. Biochemical and culture growth experiments confirmed the role of the β-oxidation pathway in aliphatic alkane degradation. Subsequently, transcriptomic analysis of H. hydrocarbonoclasticus cultured in acetate vs. acetate and hexadecane revealed that seven up-regulated genes were common in 5- and 24-h samples. Three were annotated as ribonucleoside-diphosphate reductase R2-like (RNRR2-like) genes, which were predicted to involve in the biodegradation of hexadecane. Based on the transcriptomic level, the putative functional genes were inferred from multiple isogenes. Among these genes, an important cluster encodes three enzymes for the β-oxidation pathway as well as long-chain fatty acid-CoA ligase for pre-step. The present research identified the function of the β-oxidation pathway in aliphatic alkane degradation and recognized the functional genes in haloarchaea. The mineralization of aliphatic alkane in extreme environments driven by archaea was further understood through this study.
Topics: Alkanes; Archaea; Biodegradation, Environmental; Carbon; Oxidation-Reduction
PubMed: 32328734
DOI: 10.1007/s00792-020-01167-z -
SAR and QSAR in Environmental Research Jun 2006The presence and absence of alkane isomers in petroleum and petroleum derivatives depend on the complexity of these structures. It was assumed that the more complex the...
The presence and absence of alkane isomers in petroleum and petroleum derivatives depend on the complexity of these structures. It was assumed that the more complex the structure is the less probable it is that that the molecule can be detected in any petroleum derivative. Complexity is a vague concept, which has not been defined in quantitative terms yet, and therefore there is no experimental method, which could be used to determine 'complexity'. Mass spectrometry and infrared spectroscopy in combination with gas chromatography were used to identify the various structural isomers of alkanes in petroleum ether. The isomers were categorised in quantitative terms by using topological indices and linear discriminant analysis. It was found that alkanes possessing a more complex, highly branched structure are less probable to be detected in petroleum ether than isomers with a simpler backbone structure. It was proposed that the experimental 'measure' of the complexity of isomer(i) should be proportional to 1/C(i), where C(i), denotes the concentration of isomer(i) in a (primary) petroleum derivative.
Topics: Alkanes; Gas Chromatography-Mass Spectrometry; Isomerism
PubMed: 16815771
DOI: 10.1080/10659360600787791 -
The Journal of Physical Chemistry. A Dec 2008Alkane hydroxylation by peroxy acids proceeds by a synchronous nonconcerted peroxy oxygen insertion into the C-H bond according to density functional theory. A...
Alkane hydroxylation by peroxy acids proceeds by a synchronous nonconcerted peroxy oxygen insertion into the C-H bond according to density functional theory. A comparable reaction sequence, initiated by homolytic peroxy bond cleavage, can be formulated for the alkane hydroxylation by the cytochrome P450 hydroperoxo-heme Compound 0. This hydroxylation reaction proceeds by a two-step process because the formed reactive intermediate, Compound II, is significantly stabilized.
Topics: Alkanes; Butanes; Catalysis; Cytochrome P-450 Enzyme System; Hydroxylation; Models, Molecular; Molecular Conformation; Peroxides; Porphyrins; Propane; Thermodynamics
PubMed: 18956858
DOI: 10.1021/jp801720s -
Analytical Biochemistry Jul 2020Metabolite profiling in anaerobic alkane biodegradation plays an important role in revealing activation mechanisms. Apart from alkylsuccinates, which are considered to...
Metabolite profiling in anaerobic alkane biodegradation plays an important role in revealing activation mechanisms. Apart from alkylsuccinates, which are considered to be the usual biomarkers via fumarate addition, the downstream metabolites of C-skeleton rearrangement can also be regarded as biomarkers. However, it is difficult to detect intermediate metabolites in both environmental samples and enrichment cultures, resulting in lacking direct evidence to prove the occurrence of fumarate addition pathway. In this work, a synthetic method of rearrangement metabolites was established. Four compounds, namely, propylmalonic acid, 2-(2-methylbutyl)malonic acid, 2-(2-methylpentyl)malonic acid and 2-(2-methyloctyl)malonic acid, were synthesized and determined by four derivatization approaches. Besides, their mass spectra were obtained. Four characteristic ions were observed at m/z 133 + 14n, 160 + 28n, 173 + 28n and [M - (45 + 14n)] (n = 0 and 2 for ethyl and n-butyl esters, respectively). For methyl esterification, mass spectral features were m/z 132, 145 and [M - 31], while for silylation, fragments were m/z 73, 147, 217, 248, 261 and [M - 15]. These data provide basis on identification of potential rearrangement metabolites in anaerobic alkane biodegradation via fumarate addition.
Topics: Alkanes; Anaerobiosis; Fumarates; Malonates; Mass Spectrometry
PubMed: 32333904
DOI: 10.1016/j.ab.2020.113746 -
Applied and Environmental Microbiology Jan 2024Many species can grow on -alkanes of varying lengths (≤C40). AlmA, a unique flavoprotein in these strains, is the only enzyme proven to be required for the...
Many species can grow on -alkanes of varying lengths (≤C40). AlmA, a unique flavoprotein in these strains, is the only enzyme proven to be required for the degradation of long-chain (LC) -alkanes, including C32 and C36 alkanes. Although it is commonly presumed to be a terminal hydroxylase, its role in -alkane degradation remains elusive. In this study, we conducted physiological, biochemical, and bioinformatics analyses of AlmA to determine its role in -alkane degradation by ADP1. Consistent with previous reports, gene deletion analysis showed that was vital for the degradation of LC -alkanes (C26-C36). Additionally, enzymatic analysis revealed that AlmA catalyzed the conversion of aliphatic 2-ketones (C10-C16) to their corresponding esters, but it did not conduct -alkane hydroxylation under the same conditions, thus suggesting that AlmA in strain ADP1 possesses Baeyer-Villiger monooxygenase (BVMO) activity. These results were further confirmed by bioinformatics analysis, which revealed that AlmA was closer to functionally identified BVMOs than to hydroxylases. Altogether, the results of our study suggest that LC -alkane degradation by strain ADP1 possibly follows a novel subterminal oxidation pathway that is distinct from the terminal oxidation pathway followed for short-chain -alkane degradation. Furthermore, our findings suggest that AlmA catalyzes the third reaction in the LC -alkane degradation pathway.IMPORTANCEMany microbial studies on -alkane degradation are focused on the genes involved in short-chain -alkane (≤C16) degradation; however, reports on the genes involved in long-chain (LC) -alkane (>C20) degradation are limited. Thus far, only AlmA has been reported to be involved in LC -alkane degradation by spp.; however, its role in the -alkane degradation pathway remains elusive. In this study, we conducted a detailed characterization of AlmA in ADP1 and found that AlmA exhibits Baeyer-Villiger monooxygenase activity, thus indicating the presence of a novel LC -alkane biodegradation mechanism in strain ADP1.
Topics: Mixed Function Oxygenases; Alkanes; Oxidation-Reduction; Acinetobacter
PubMed: 38168668
DOI: 10.1128/aem.01625-23 -
Journal of Biotechnology Apr 2012Synthetic alkane-inducible biosensors have applications as detectors for environmental hydrocarbon contamination and as novel inducible expression systems with low-cost...
Synthetic alkane-inducible biosensors have applications as detectors for environmental hydrocarbon contamination and as novel inducible expression systems with low-cost inducers. Here, we have assembled and evolved an alkane-responsive biosensor with a fluorescence output signal in Escherichia coli by utilizing regulatory machinery from Pseudomonas putida's alkane metabolism. Within our system, the transcriptional regulator, AlkSp, is activated by the presence of alkanes and binds to the P(alkB) promoter, stimulating transcription of a Green Fluorescent Protein reporter. Through two successive rounds of directed evolution via error prone PCR and fluorescence activated cell sorting, we isolated alkS mutants enabling up to a 5 fold increase in fluorescence output signal in response to short-chain alkanes such as hexane and pentane. Further characterization of selected mutants demonstrated altered responsiveness to a wide range of linear alkanes (pentane to dodecane). Sequence analysis highlighted the S470T mutation as a likely candidate responsible for increased effectiveness of the AlkS protein for short-chain alkanes. This work represents the first evolution of a synthetic biosensor system for alkanes.
Topics: Alkanes; Amino Acid Substitution; Biosensing Techniques; Escherichia coli; Green Fluorescent Proteins; Mutation, Missense; Promoter Regions, Genetic; Pseudomonas putida; Recombinant Proteins
PubMed: 22326628
DOI: 10.1016/j.jbiotec.2012.01.028 -
ChemSusChem Jan 2015Alkane dehydrogenation is of special interest for basic science but also offers interesting opportunities for industry. The existing dehydrogenation methodologies make...
Alkane dehydrogenation is of special interest for basic science but also offers interesting opportunities for industry. The existing dehydrogenation methodologies make use of heterogeneous catalysts, which suffer from harsh reaction conditions and a lack of selectivity, whereas homogeneous methodologies rely mostly on unsolicited waste generation from hydrogen acceptors. Conversely, acceptorless photochemical alkane dehydrogenation in the presence of trans-Rh(PMe3 )2 (CO)Cl can be regarded as a more benign and atom efficient alternative. However, this methodology suffers from catalyst deactivation over time. Herein, we provide a detailed investigation of the trans-Rh(PMe3 )2 (CO)Cl-photocatalyzed alkane dehydrogenation using spectroscopic and theoretical investigations. These studies inspired us to utilize CO2 to prevent catalyst deactivation, which leads eventually to improved catalyst turnover numbers in the dehydrogenation of alkanes that include liquid organic hydrogen carriers.
Topics: Alkanes; Carbon Dioxide; Catalysis; Hydrogenation; Models, Molecular; Molecular Conformation; Photochemical Processes
PubMed: 25346450
DOI: 10.1002/cssc.201402850