Development of bioremediation processes under anoxic conditions using denitrifying bacteria

1)微生物在厌氧条件下降解芳香族化合物的菌群分析在厌氧条件下降解芳香族化合物的细菌主要是Thauera属和Azoarcus属的限制性菌株。在本项目中，我们已经分离出了一些新的细菌菌株，属于属磁细菌。通过16 S rDNA系统发育分析，将菌株分为3个类群，这3个类群对应于菌株对芳香族化合物的利用率。2）菌株对芳香族化合物的降解途径（1）Thauera sp. DNT-1对甲苯的降解：该菌在好氧和厌氧条件下均能降解甲苯。克隆了甲苯双加氧酶（Tod）和苄基琥珀酸合成酶（Bss）。从基因转录分析的结果来看，Bss只能在厌氧条件下起作用，而tod基因产物在有氧条件下起作用。(2)磁细菌降解甲苯基因的克隆。从磁链菌TS-6中克隆到了编码甲苯降解主要酶的基因。3）原位生物修复条件下降解菌的归属研究发现苯甲酰辅酶A还原酶是多种甲苯厌氧降解菌开环的关键酶。我们提出了一个监测系统的厌氧芳香族化合物降解苯甲酰辅酶A还原酶基因作为探针。

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.