Taxonomic characterization of denitrifying bacteria that degrade aromatic compounds and description of Azoarcus toluvorans sp. nov. and Azoarcus toluclasticus sp. nov.

Abstract

A taxonomic characterization of twenty-one strains capable of degrading aromatic compounds under denitrifying conditions, isolated from ten different geographical locations, was performed on the basis of general morphological and physiological characteristics, cellular fatty acids, DNA base composition, small ribosomal (165) subunit DNA sequences, whole-cell protein patterns and genomic DNA fragmentation analysis, in addition to DNA similarity estimations using hybridization methods. The collection of strains was subdivided into a number of different groups. A first group, consisting of four strains, could be assigned to the previously described species Azoarcus tolulyticus. A second group (five strains) had DNA which reannealed highly to that of strains of the first group, and it is considered to represent a genomovar of A. tolulyticus. The third and fourth groups, composed of a total of five strains, represent a new species of Azoarcus, Azoarcus toluclasticus (group 3 ) and a genomovar of this species (group 4), respectively. Finally, the fifth group, with two strains, corresponds to another new species of the genus Azoarcus, Azoarcus toluvorans. In addition to these five groups, the collection includes five individual strains perhaps representing as many different new species, The above classification is partially consistent with the results of approaches other than DNA-DNA hybridization (electrophoretic patterns of whole-cell proteins and of the fragments obtained after digestion of total DNA with infrequently cutting restriction enzymes). On the other hand, no correlation of these groupings was found in terms of the cellular fatty acid composition. It is also unfortunate that no simple sets of easily determinable phenotypic properties could be defined as being characteristic of each of the groups.

Tepidiphilus margaritifer gen. nov., sp. nov., isolated from a thermophilic aerobic digester

“…Phylogenetic analysis of the 16S rDNA sequence of strain N2-214 T showed its affiliation to the b-Proteobacteria, a result that is in agreement with the polar lipid and respiratory quinone composition (see below). The 16S rDNA sequence was then compared with all species with validly published names of the most closely related genera, Azoarcus, Thauera and Hydrogenophilus (Springer et al, 1998;Hayashi et al, 1999;Song et al, 1998Song et al, , 1999Song et al, , 2000Song et al, , 2001Reinhold-Hurek & Hurek, 2000;Stöhr et al, 2001;Mechichi et al, 2002), and several other genera in the b-Proteobacteria. The 16S rDNA sequence of strain N2-214 T was not closely related to those of other genera within this subclass, the highest similarities (approx.…”

Characterization of halobenzoate-degrading, denitrifying Azoarcus and Thauera isolates and description of Thauera chlorobenzoica sp. nov.

“…T. selenatis was grown in a vitaminamended medium as described previously (Song et al 2000a) and T. mechernichensis was cultured aerobically in LuriaBertani broth. All of the strains of Azoarcus were grown on M-R2A medium as described previously (Song et al, 1999).…”

“…Later, a new species capable of degrading aromatic compounds was described under the name Azoarcus evansii (Anders et al, 1995). Toluene-degrading denitrifiers were initially assigned to a new species, Azoarcus tolulyticus (Zhou et al, 1995), but more detailed taxonomic examination resulted in reclassification and the proposal of two additional species, Azoarcus toluvorans and Azoarcus toluclasticus (Song et al, 1999). Finally, the species Azoarcus anaerobius was assigned to the genus as an obligately denitrifying bacterium with the capacity to degrade α-resorcinol (Springer et al, 1998).…”

“…Several bacterial strains capable of growing at the expense of aromatic compounds under denitrifying conditions have been assigned to the genera Azoarcus and Thauera (Anders et al, 1995 ;Gallus et al, 1997 ;Harms et al, 1999 ;Ha$ ggblom & Young, 1999 ;Rabus & Widdel, 1995 ;van Schie & Young, 1998 ;Song et al, 1998Song et al, , 1999Song et al, , 2000aSpringer et al, 1998 ;Zhou et al, 1995). These closely related genera seem to constitute a major group of denitrifying bacteria capable of degrading aromatic compounds.…”

Biology of Pseudomonas stutzeri

“…(336). It could be applied to other well-defined genomic groups in species such as Shewanella putrefaciens and Bacillus cereus, etc.…”