Desulfitobacterium aromaticivorans sp. nov. and Geobacter toluenoxydans sp. nov., iron-reducing bacteria capable of anaerobic degradation of monoaromatic hydrocarbons

Dissimilatory iron reduction plays a significant role in subsurface environments. Currently, it is assumed that members of the genus Geobacter constitute the majority of the iron-reducing micro-organisms that oxidize aromatic compounds in contaminated subsurface environments. Here, we report the isolation of two phylogenetically distinct pure cultures of iron-reducing degraders of monoaromatic hydrocarbons, strain TMJ1 T , which belongs to the genus Geobacter within the Deltaproteobacteria , and strain UKTL T , belonging to the genus Desulfitobacterium within the Clostridia . Both strains utilize a wide range of substrates as carbon and energy sources, including the aromatic compounds toluene, phenol and p -cresol. Additionally, strain UKTL T utilizes o -xylene and TMJ1 T utilizes m -cresol. Anaerobic degradation of toluene in both strains and o -xylene in strain UKTL T is initiated by activation with fumarate addition to the methyl group. The genomic DNA G+C contents of strains TMJ1 T and UKTL T are 54.4 and 47.7 mol%, respectively. Based on a detailed physiological characterization and phylogenetic analysis of the 16S rRNA genes of both strains, we propose the names Desulfitobacterium aromaticivorans sp. nov. (type strain UKTL T =DSM 19510 T =JCM 15765 T ) and Geobacter toluenoxydans sp. nov. (type strain TMJ1 T =DSM 19350 T =JCM 15764 T ) to accommodate these strains. To the best of our knowledge, strain UKTL T is the first described spore-forming, iron-reducing bacterium that can degrade aromatic hydrocarbons.