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Toluene Dioxygenase (toluene + dioxygenase)
Selected AbstractsEffect of sorption and desorption resistance on aerobic trichloroethylene biodegradation in soilsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2002Sangjin Lee Abstract Biodegradation of trichloroethylene(TCE) by toluene-degrading bacteria was measured under aerobic conditions in aqueous and soil-slurry batch microcosms. For soil-phase experiments, a freshly contaminated soil and a soil containing only the desorption-resistant fraction of TCE were tested. In both cases, presence of soil resulted in biodegradation rates substantially lower than those determined in the absence of soil. In aqueous-phase experiments, an appreciable increase in the rate and extent of TCE biodegradation was observed in microcosms when toluene was added multiple times. The TCE degradation rates were clearly correlated with toluene dioxygenase (TOD) enzyme activity over time, thus providing an indication of the cometabolic pathway employed by the microbial population. In soil-slurry experiments containing freshly contaminated soil, a TCE degradation rate of approximately 150 ,g TCE/kg/h was observed during the first 39-h period, and then the TCE degradation rate slowed considerably to 0.59 and 0.84 ,g TCE/kg/h for microcosms receiving one and two additions of toluene, respectively. The TCE degradation rates in soil-slurry microcosms containing the desorption-resistant fraction of TCE-contaminated soil were approximately 0.27 and 0.32 ,g TCE/kg/h in microcosms receiving one and two additions of toluene, respectively. It is clear from these results that mass transfer into the aqueous phase limited bioavailability of TCE in the contaminated soil. [source] Evolution of a degradative bacterial consortium during the enrichment of naphtha solventJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2000L. Cavalca A microbial mixed culture able to degrade naphtha solvent, a model of hydrocarbon aromatic mixture, was isolated from a hydrocarbon-polluted soil. Composition of the population was monitored by phenotypic and molecular methods applied on soil DNA, on whole enrichment culture DNA, and on 85 isolated strains. Strains were characterized for their 16S rDNA restriction profiles and for their random amplified polymorphic DNA profiles. Catabolic capabilities were monitored by phenotypic traits and by PCR assays for the presence of the catabolic genes methyl mono-oxygenase ( xylA,M), catechol 2,3 dioxygenase (xylE) and toluene dioxygenase (todC1) of TOL and TOD pathways. Different haplotypes belonging to Pseudomonas putida, Ps. aureofaciens and Ps. aeruginosa were found to degrade aromatic compounds and naphtha solvent. The intrinsic catabolic activity of the microbial population of the polluted site was detected by PCR amplification of the xylE gene directly from soil DNA. [source] Production of dyestuffs from indole derivatives by naphthalene dioxygenase and toluene dioxygenaseLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2003J.Y. Kim Abstract Aims: To isolate and characterize the phorate [O,O-diethyl-S-(ethylthio)methyl phosphoradiothioate] degrading bacteria from agricultural soil, and their assessment for multifarious biological activities of environmental and agronomic significance. Methods and Results: Based on their morphological and biochemical characteristics, the selected isolates PS-1, PS-2 and PS-3 were presumptively identified as Rhizobium, Pseudomonas and Proteus species, respectively. The HPLC analysis of phorate in bioaugmented soil revealed its complete disappearance within 40 days. The degradation isotherms of the isolates PS-1, PS-2 and PS-3 suggested time-dependent disappearance of phorate following the first-order rate kinetics at the corresponding rate constants of 0.04, 0.05 and 0.04 d,1. Besides, the isolates concurrently exhibited substantial phosphate solubilization, indole acetic acid (IAA) and siderophore production, as well as limited biocontrol activity against fungal phytopathogens. Conclusions, Significance and Impact of the Study: The data revealed the potential of isolates for collateral plant growth promotion, biocontrol and bioremediation. The selected strains may serve as an important bioresource for development of effective super-bioinoculants. [source] Enzyme-Catalysed Synthesis and Absolute Configuration Assignments of cis -Dihydrodiol Metabolites from 1,4-Disubstituted BenzenesCHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2007Derek Abstract A series of ten cis -dihydrodiol metabolites has been obtained by bacterial biotransformation of the corresponding 1,4-disubstituted benzene substrates using Pseudomonas putida UV4, a source of toluene dioxygenase (TDO). Their enantiomeric excess (ee) values have been established using chiral stationary phase HPLC and 1H,NMR spectroscopy. Absolute configurations of the majority of cis -dihydrodiols have been established using stereochemical correlation and X-ray crystallography and the remainder have been tentatively assigned using NMR spectroscopic methods but finally confirmed by circular dichroism (CD) spectroscopy. These configurational assignments support and extend the validity of an empirical model, previously used to predict the preferred stereochemistry of TDO-catalysed cis -dihydroxylation of ten 1,4-disubstituted benzene substrates, to more than twenty-five examples. [source] | ||||||||||