Development of bioremediation processes under anoxic conditions using denitrifying bacteria

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1) Analysis of microbial consortia for degradation of aromatic compounds under denitrifying conditionsBacteria that degrade aromatic compounds under denitrifying conditions had been restricted strains belonging to genera Thauera and Azoarcus. In this project, we have isolated a number of novel bacterial strains that belonged to genus Magnetospirillum. The isolates were divided into 3 groups through phylogenetic analysis with 16S rDNA, which correspond to availability of aromatic compounds for growth.2) Pathway for degradation of aromatic compounds by the isolates(1) Toluene degradation by Thauera sp. DNT-1: The organism was found to be able to degrade toluene under both aerobic and denitrifying conditions. Toluene dioxygenase (Tod) and benzyl succinate synthase (Bss) were cloned. From the results of transcriptional analyses of the genes, Bss could be effective only under anaerobic conditions, while tod gene product functioned under aerobic conditions.(2) Cloning of genes for toluene degradation by Magnetospirillum spp. The genes encoding main enzymes participating in toluene degradation under denitrifying conditions were cloned from Magnetospirillum sp. TS-6. From the result, the degradation pathway of the organism could be confirmed.3) Assignment of the denitrifying bacteria under in-situ-bioremediationBenzoyl CoA reductase was found as a key enzyme for the ring fission a variety of anaerobic toluenedegraders. We proposed a monitoring system for anaerobic aromatic-compound-degraders using benzoyl CoA reductase genes as the probe.