Oxidation of dimethyl sulfide by various aromatic compound oxygenases from bacteria
ABSTRACT As a result of the determination of dimethyl sulfide (DMS) oxidizing activity of bacterial aromatic compound oxygenases, multicomponent monooxygenases (DmpKLMNOP from Pseudomonas sp. CF600, AphKLMNOP from Comamonas testosteroni TA441, and TodABCDEF from Pseudomonas sp. JS150), single component monooxygenases (TfdB from Pseudomonas putida EST4011 and XylMA from Pseudomonas putida mt-2), and dioxygenases (CumA1A2A3A4 from Pseudomonas fluorescens IP01 and PahAaAbAcAd from Pseudomonas putida OUS82) showed DMS-oxidizing activity, while CarAaAcAd from Pseudomonas sp. CA10 and SoxC from Rhodococcus sp. IGTS8 did not. These results indicate the possibilities that these oxygenases might oxidize DMS to DMSO under the natural condition in the environment.
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ABSTRACT: The chemical composition of volatile organic compounds (VOCs) in soil gases from the Solfatara crater (Campi Flegrei, Italy) was analyzed to investigate the effects of biogeochemical processes on gases discharged from the hydrothermal reservoir and released into the atmosphere through diffuse degassing. The chemistry of fluids from fumarolic vents, which represent preferential pathways for fluid uprising, was also reported for comparison. Oxidation-reduction and hydration-dehydration reactions, as well as microbial activity, strongly affected the composition of C4-C9 alkanes, alkenes, S-bearing compounds and alkylated aromatics, especially in those sites where the soil showed relatively low permeability to uprising fluids. Other endogenous organic compounds, such as benzene, phenol and hydrofluorocarbons were able to transit through the soil almost undisturbed, independently on the gas emission rate. Products of VOC degradation mainly consisted of aldehydes, ketones, esters, ethers and, subordinately, alcohols. Cyclic compounds revealed the occurrence of VOCs produced within sedimentary formations overlying the hydrothermal reservoir, whereas the presence of chlorofluorocarbons (CFCs) was likely related to air contamination. The results of the present study highlighted the strict control of biogeochemical processes on the behaviour of hydrothermal VOCs that, at least at a local scale, may have a significant impact on air quality. This information could be improved by laboratory experiments conducted at specific chemical-physical conditions and in presence of different microbial populations.Applied Geochemistry 02/2015; 56. DOI:10.1016/j.apgeochem.2015.02.005 · 2.02 Impact Factor
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ABSTRACT: The composition of non-methane volatile organic compounds (hereafter VOCs) in i) the cover soil, at depths of 30, 50 and 70 cm, and ii) gas recovery wells from Case Passerini landfill site, (Florence, Italy) was determined by GC-MS. The study, based on the analysis of interstitial gases sampled along vertical profiles within the cover soil, was aimed to investigate the VOC behaviour as biogas transits from a reducing to a relatively more oxidizing environment. A total of 48 and 63 different VOCs were identified in the soil and well gases, respectively. Aromatics represent the dominant group (71.5% of total VOC) in soil gases, followed by alkanes (6.8%), ketones (5.7%), organic acids (5.2%), aldehydes (3.0%), esters (2.6%), halogenated compounds (2.1%) and terpenes (1.3%). Cyclics, heterocyclics, S-bearing compounds and phenols are <or=1%. In the wells the VOC composition is characterized by higher concentrations of cyclic (7.6%) and S-bearing compounds (2%) and lower concentrations of O-bearing compounds. The vertical distribution of VOCs in the cover soil shows significant variations: alkanes, aromatics and cyclics decrease at decreasing depth, whereas an inverse trend is displayed by the O-bearing species. Total VOC and CH(4) concentrations at a depth of 30 cm in the soil are comparable, inferring that microbial activity is likely affecting VOCs at a very minor extent with respect to CH(4). According to these considerations, to assess the biogas emission impact, usually carried out on the sole basis of CO(2) and CH(4) emission rates, the physical-chemical behaviour of VOCs in the cover soil, regulating the discharge of these highly contaminant compounds in ambient air, has to be taken into account. The soil vertical distribution of these species can be used to better evaluate the efficiency of oxidative capability of intermediate and final covers.Science of The Total Environment 06/2009; 407(15):4513-25. DOI:10.1016/j.scitotenv.2009.04.022 · 4.10 Impact Factor
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ABSTRACT: Based on structural, biochemical, and genetic data, the soluble diiron monooxygenases can be divided into four groups: the soluble methane monooxygenases, the Amo alkene monooxygenase of Rhodococcus corallinus B-276, the phenol hydroxylases, and the four-component alkene/aromatic monooxygenases. The limited phylogenetic distribution of these enzymes among bacteria, together with available genetic evidence, indicates that they have been spread largely through horizontal gene transfer. Phylogenetic analyses reveal that the alpha- and beta-oxygenase subunits are paralogous proteins and were derived from an ancient gene duplication of a carboxylate-bridged diiron protein, with subsequent divergence yielding a catalytic alpha-oxygenase subunit and a structural beta-oxygenase subunit. The oxidoreductase and ferredoxin components of these enzymes are likely to have been acquired by horizontal transfer from ancestors common to unrelated diiron and Rieske center oxygenases and other enzymes. The cumulative results of phylogenetic reconstructions suggest that the alkene/aromatic monooxygenases diverged first from the last common ancestor for these enzymes, followed by the phenol hydroxylases, Amo alkene monooxygenase, and methane monooxygenases.FEMS Microbiology Reviews 11/2003; 27(4):449-79. DOI:10.1016/S0168-6445(03)00023-8 · 13.81 Impact Factor