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  • 1
    Electronic Resource
    Electronic Resource
    Anaerobic transformation of 2,4,6-trinitrotoluene (TNT) (1993)
    Springer
    Archives of microbiology 159 (1993), S. 345-353 
    Details
    ISSN: 1432-072X
    Keywords: TNT degradation ; Polynitroaromatic compounds ; Sulfite reductase ; Carbon monoxide dehydrogenase ; Hydrogenase ; Ferredoxin ; Sulfidogenic bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A sulfate-reducing bacterium using trinitrotoluene (TNT) as the sole nitrogen source was isolated with pyruvate and sulfate as the energy sources. The organism was able to reduce TNT to triaminotoluene (TAT) in growing cultures and cell suspensions and to further transform TAT to still unknown products. Pyruvate, H2, or carbon monoxide served as the electron donors for the reduction of TNT. The limiting step in TNT conversion to TAT was the reduction of 2,4-diamino-6-nitrotoluene (2,4-DANT) to triaminotoluene. The reduction proceeded via 2,4-diamino-6-hydroxylaminotoluene (DAHAT) as an intermediate. The intermediary formation of DAHAT was only observed in the presence of carbon monoxide or hydroxylamine, respectively. The reduction of DAHAT to triaminotoluene was inhibited by both CO and NH2OH. The inhibitors as well as DANT and DAHAT significantly inhibited sulfide formation from sulfite. The data were taken as evidence for the involvement of dissimilatory sulfite reductase in the reduction of DANT and/or DAHAT to triaminotoluene. Hydrogenase purified from Clostridium pasteurianum and carbon monoxide dehydrogenase partially purified from Clostridium thermoaceticum also catalyzed the reduction of DANT in the presence of methyl viologen or ferredoxin, however, as the main reduction product DAHAT rather than triaminotoluene was formed. The findings could explain the function of CO as an electron donor for the DANT reduction (to DAHAT) and the concomitant inhibitory effect of CO on triaminotoluene formation (from DAHAT) by the inhibition of sulfite reductase. Triaminotoluene is further anaerobically converted to unknown products by the isolate under sulfate-reducing and by a Pseudomonas strain under denitrifying conditions. Triaminotoluene conversion was also catalyzed in the absence of cells under aerobic conditions by trace elements, especially by Mn2+, accompanied by the elimination of ammonia in a stoichiometry of 1 NH3 released per TAT transformed. The results might be of interest for the bioremediation of wastewater polluted with nitroaromatic compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00290917
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  • 2
    Electronic Resource
    Electronic Resource
    Studies on tetrachloroethene respiration inDehalospirillum multivorans (1996)
    Springer
    Archives of microbiology 166 (1996), S. 379-387 
    Details
    ISSN: 1432-072X
    Keywords: Dehalospirillum multivorans ; Reductive dechlorination ; Tetrachloroethene respiration ; Trichloroethene ; PCE dehalogenase ; Formate dehydrogenase ; Fumarate respiration ; Hydrogenase ; Electron transport chain ; Reversed electron flow ; Ferredoxin ; Menaquinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tetrachloroethene (PCE) respiration was studied in the tetrachloroethene-utilizing anaerobe,Dehalospirillum multivorans, with respect to localization of the catabolic enzymes, the electron carriers potentially involved in electron transport, and the response to ionophores and specific inhibitors. Hydrogenase and formate dehydrogenase were recovered in the periplasmic cell fraction and were membrane-associated. Electron-accepting tetrachloroethene dehalogenase was found in the cytoplasmic fraction. In the PCE dehalogenase assay, only artificial electron donors with a standard redox potential of 〈-360 mV were effective electron donors for PCE reduction. Besides these artificial reductants, ferredoxin isolated fromD. multivorans (E′o=-445 mV) could serve as electron donor for PCE reduction. However, the reaction rate with ferredoxin was only 1% of that with methyl viologen, whereas the pyruvate-ferredoxin oxidoreductase exhibited almost the same reaction rates with methyl viologen and ferredoxin as electron acceptors for pyruvate oxidation. Reduced menadione (2-methyl-1,4-naphthoquinone) did not serve as electron donor in the PCE dehalogenase reaction. 2-Heptyl-4-hydroxyquinoline-N-oxide (HOQNO) had no significant effect on PCE dechlorination in cell suspensions and in crude extracts. Whole cells catalyzed the reductive dechlorination of PCE with H2 or formate as electron donors. The dechlorination in cell suspensions rather than in cell extracts was inhibited by the ionophores carbonylcyanide-p-(trifluoromethoxy)-phenylhydrazone (FCCP) and tetrachlorosalicylanilide (TCS), indicating that a membrane potential and/or a pH gradient may be required for the reaction in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01682983
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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