Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.17 (PCE)
 1,301 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two tetrachlorethene (PCE)-dechlorinating populations, designated strains BB1 and BRS1, were isolated from pristine river sediment and chloroethene-contaminated aquifer material, respectively. PCE-to-cis-1,2-dichloroethene-dechlorinating activity could be transferred in defined basal salts medium with acetate as the electron donor and PCE as the electron acceptor. Taxonomic analysis based on 16S rRNA gene sequencing placed both isolates within the Desulfuromonas cluster in the delta subdivision of the Proteobacteria. PCE was dechlorinated at rates of at least 139 nmol min(-1) mg of protein(-1) at pH values between 7.0 and 7.5 and temperatures between 25 and 30 degrees C. Dechlorination also occurred at 10 degrees C. The electron donors that supported dechlorination included acetate, lactate, pyruvate, succinate, malate, and fumarate but not hydrogen, formate, ethanol, propionate, or sulfide. Growth occurred with malate or fumarate alone, whereas oxidation of the other electron donors depended strictly on the presence of fumarate, malate, ferric iron, sulfur, PCE, or TCE as an electron acceptor. Nitrate, sulfate, sulfite, thiosulfate, and other chlorinated compounds were not used as electron acceptors. Sulfite had a strong inhibitory effect on growth and dechlorination. Alternate electron acceptors (e.g., fumarate or ferric iron) did not inhibit PCE dechlorination and were consumed concomitantly. The putative fumarate, PCE, and ferric iron reductases were induced by their respective substrates and were not constitutively present. Sulfide was required for growth. Both strains tolerated high concentrations of PCE, and dechlorination occurred in the presence of free-phase PCE (dense non-aqueous-phase liquids). Repeated growth with acetate and fumarate as substrates yielded a BB1 variant that had lost the ability to dechlorinate PCE. Due to the 16S rRNA gene sequence differences with the closest relatives and the unique phenotypic characteristics, we propose that the new isolates are members of a new species, Desulfuromonas michiganensis, within the Desulfuromonas cluster of the Geobacteraceae.
 ...
PMID:Characterization of two tetrachloroethene-reducing, acetate-oxidizing anaerobic bacteria and their description as Desulfuromonas michiganensis sp. nov. 1273 73

Pretreatment zones (PTZs) composed of sand, 10% zero-valent iron [Fe(0)]/sand, and 10% pyrite (FeS2)/sand were examined for their ability to prolong Fe(0) reactivity in above ground column reactors and a subsurface permeable reactive barrier (PRB). The test site had an acidic, oxic aquifer contaminated with tetrachloroethylene (PCE) and trichloroethylene (TCE). The 10% FeS2 and 10% Fe(0) PTZs removed dissolved oxygen and affected the pH and E(h) in the PTZ. None of the PTZs had any effect on pH or E(h) in the 100% Fe(0) zone. Nitrate and sulfate were removed more quickly in the Fe(0) zones preceded by either the 10% Fe(0) PTZ or 10% FeS2. PCE first-order degradation rate constants (k(obs)) decreased significantly (> 80%) with increasing column pore volumes regardless of the PTZ material used. k(obs) finally leveled off after approximately 1 yr of operation. The column results predict that the PRB will experience a breakthrough of PCE in 3-5 yr and illustrate the importance of incorporating temporal variations in degradation rate constants when designing PRBs.
 ...
PMID:Use of pretreatment zones and zero-valent iron for the remediation of chloroalkenes in an oxic aquifer. 1285 26

Reductive biotransformation of tetrachloroethene (PCE) to ethene occurred during anaerobic degradation of toluene in an enrichment culture. Ethene was detected as a dominant daughter product of PCE dechlorination with negligible accumulation of other partially chlorinated ethenes. PCE dechlorination was linked to toluene degradation, as evidenced by the findings that PCE dechlorination was limited in the absence of toluene but was restored with a spike of toluene again in the cultures. PCE was effectively dechlorinated in cultures amended with a wide range of concentrations of PCE and toluene. PCE dechlorination can be described by a Monod-like equation but followed a zero-order kinetic at high levels of PCE. In addition to toluene, benzoate and lactate were also able to be used as sole electron donors for reductive dechlorination of PCE in the cultures. In terms of dechlorination rates, lactate was the best electron donor followed by benzoate and then toluene. The kinetic characteristics of PCE dechlorination were retained in the cultures regardless of electron donors used, but the kinetic constant values were unique to each electron donor. The dechlorination rate was found to be closely correlated with the level of H2 produced during fermentation of the three organic compounds. Nitrate and sulfate were observed to be favorable electron acceptors in this culture, and their presence completely blocked electron flow to PCE. However, the presence of nitrate and sulfate did not destroy the capability of PCE dechlorination by the culture. PCE dechlorination was immediately reestablished after depletion of nitrate and sulfate in the culture. This anaerobic process provides an opportunity for concurrent remediation of chlorinated solvents and certain fuel hydrocarbons, and recognition of this process is also important in understanding the subsurface fate and transport of these contaminants under natural conditions.
 ...
PMID:Reductive biotransformation of tetrachloroethene to ethene during anaerobic degradation of toluene: experimental evidence and kinetics. 1638 54