Untersuchungen zum anaeroben Toluol-Stoffwechsel in fakultativ und obligat aneroben Bakterien

The strictly anaerobic Deltaproteobacteria Geobacter metallireducens and Desulfobacula toluolica are able to use toluene as sole energy- and carbon source. The degradation of toluene proceeds similar to that in the denitrifying organism Thauera aromatica. In the initial step (R)-benzylsuccinate is generated from toluene and fumarate which is catalyzed by the enzyme (R)-benzylsuccinate synthase. The further degradation of (R)-benzylsuccinate is carried out in a modified b-oxidation to the central intermediate benzoyl-CoA.In an early step of the b-oxidation (R)-benzylsuccinate is oxidized to (E)-phenylitaconyl-CoA.Beside the (R)-benzylsuccinyl-CoA dehydrogenase (BbsG), there is also an electron transferring flavoprotein (EtfBA) involved. In contrast to facultative anaerobic organisms like T. aromatica for example, the genes etfB and etfA of the two subunits of the electron transferring flavoprotein of G. metallireducens and D. toluolica are coded in the bbs-operon (betaoxidation of benzylsuccinate). Aim of this work was to characterize the electron transferring flavoprotein and the (R)-benzylsuccinate synthase from the corresponding organisms.