Project description:Two mycobacterial strains previously isolated from fossil-fuel-contaminated environments and shown to degrade four- and/or five-ring polycyclic aromatic hydrocarbons were further characterized. The two strains, PYR-I and RJGII-135, had similar growth characteristics, colony morphologies, and scotochromogenic pigmentations. DNA amplification fingerprints obtained with total genomic DNA indicated some strain similarities but with several distinctly different bands. Moreover, phylogenetic analysis based upon essentially full-length 16S rRNA gene sequences separates the two strains as distinct species within the fast-growing group of mycobacteria. Although both strains are thermosensitive, strain PYR-I has the bulged U between positions 184 and 193 characteristic of thermotolerant mycobacteria. Both strains are of potential use for reintroduction into and bioremediation of polycyclic aromatic hydrocarbon-contaminated soils.
Project description:A contorted polycyclic aromatic hydrocarbon (PAH) in the shape of a monkey saddle has been synthesized in three steps from a readily available truxene precursor. The monkey saddle PAH is consisting of three five-, seven six-, and three eight-membered rings and has been unambiguously characterized by single-crystal X-ray diffraction. Owing to the three biaryl axes the monkey saddle PAH is inherently chiral. The inversion of the two enantiomeric structures into each other preferably occurs through a twisting of peripheral rings rather than by a fully planar intermediate, as has been calculated by DFT methods. Enantiomers were separated by chiral HPLC and inversion barriers determined by variable temperature circular dichroism spectroscopy, supporting the twisting mechanism.
Project description:<i>Sphingobium barthaii</i> KK22<sup>T</sup> is a high-molecular-weight polycyclic aromatic hydrocarbon-degrading soil bacterium that has been investigated in biotransformation, microbial ecology, and DNA damage studies. The complete genome sequence of <i>S. barthaii</i> revealed four closed circular sequences, including two chromosomes, a megaplasmid, and a smaller plasmid, by hybrid assembly using short- and long-read sequencing technologies.
Project description:Sphingobium sp. strain KK22 was isolated from a bacterial consortium that originated from cattle pasture soil from Texas. Strain KK22 grows on phenanthrene and has been shown to biotransform the high-molecular-weight (HMW) polycyclic aromatic hydrocarbon (PAH) benz[a]anthracene. The genome of strain KK22 was sequenced to investigate the genes involved in aromatic pollutant biotransformation.
Project description:A generic approach to the regiospecific synthesis of halogenated polycyclic aromatics is made possible by the one- or two-directional benzannulation reactions of readily available (ortho-allylaryl)trichloroacetates (the "BHQ" reaction). Palladium-catalysed cross-coupling reactions of the so-formed haloaromatics enable the synthesis of functionalised polycyclic aromatic hydrocarbons (PAHs) with surgical precision. Overall, this new methodology enables the facile mining of chemical space in search of new electronic functional materials.
Project description:We report a modular synthetic strategy for accessing heteroatom-containing polycyclic aromatic hydrocarbons (PAHs). Our approach relies on the controlled generation of transient heterocyclic alkynes and arynes. The strained intermediates undergo in situ trapping with readily accessible oxadiazinones. Four sequential pericyclic reactions occur, namely two Diels-Alder/retro-Diels-Alder sequences, which can be performed in a stepwise or one-pot fashion to assemble four new carbon-carbon (C-C) bonds. These studies underscore how the use of heterocyclic strained intermediates can be harnessed for the preparation of new organic materials.
Project description:This study investigated a metabolic network (MN) from Mycobacterium vanbaalenii PYR-1 for polycyclic aromatic hydrocarbons (PAHs) from the perspective of structure, behavior, and evolution, in which multilayer omics data are integrated. Initially, we utilized a high-throughput proteomic analysis to assess the protein expression response of M. vanbaalenii PYR-1 to seven different aromatic compounds. A total of 3,431 proteins (57.38% of the genome-predicted proteins) were identified, which included 160 proteins that seemed to be involved in the degradation of aromatic hydrocarbons. Based on the proteomic data and the previous metabolic, biochemical, physiological, and genomic information, we reconstructed an experiment-based system-level PAH-MN. The structure of PAH-MN, with 183 metabolic compounds and 224 chemical reactions, has a typical scale-free nature. The behavior and evolution of the PAH-MN reveals a hierarchical modularity with funnel effects in structure/function and intimate association with evolutionary modules of the functional modules, which are the ring cleavage process (RCP), side chain process (SCP), and central aromatic process (CAP). The 189 commonly upregulated proteins in all aromatic hydrocarbon treatments provide insights into the global adaptation to facilitate the PAH metabolism. Taken together, the findings of our study provide the hierarchical viewpoint from genes/proteins/metabolites to the network via functional modules of the PAH-MN equipped with the engineering-driven approaches of modularization and rationalization, which may expand our understanding of the metabolic potential of M. vanbaalenii PYR-1 for bioremediation applications.
Project description:The aim of the current study is to investigate the association of polycyclic aromatic hydrocarbons (PAHs), a group of environmental pollutants, with diabetes mellitus. Animal studies link PAHs to inflammation and subsequent development of diabetes mellitus. In addition, occupational studies suggest that exposure to other aromatic hydrocarbons such as dioxins may be associated with diabetes risk in humans.We examined participants from the merged National Health and Nutrition Examination Survey 2001-2002, 2003-2004 and 2005-2006. Exposures of interest were eight urinary monohydroxy-PAHs. Our outcome was diabetes mellitus defined as a glycohemoglobin level (HbA1c) ?6.5%, a self-reported physician diagnosis of diabetes or use of oral hypoglycaemic medication or insulin. Analyses were adjusted for age, sex, body mass index, race, alcohol consumption, poverty-income ratio, total cholesterol and serum cotinine.We observed a positive association between urinary biomarkers of 1 and 2-hydroxynapthol, 2-hydroxyphenanthrene and summed low molecular weight (LMW) PAH biomarkers, and diabetes mellitus. Compared with participants with summed LMW PAH biomarkers in the lowest quartile, the multivariable-adjusted OR of diabetes mellitus among those in the highest quartile was 3.1 (95% CI 1.6 to 5.8).Urinary biomarkers of 1 and 2-hydroxynapthol, 2-hydroxyphenanthrene and summed LMW PAH biomarkers are associated with diabetes mellitus in US adults 20-65 years of age. The association of a one-time biomarker of PAH exposure has limitations commonly associated with cross-sectional studies, yet is consistent with experimental animal data and is worthy of additional consideration.