Characterization of  two aerobic ultramicrobacteria isolated from urban soil and a description of Oxalicibacterium solurbis sp. nov.

Two strains of aerobic, non-spore-forming, Gram-negative, rod-shaped bacteria (ND5 and MY14^T), previously isolated from urban soil using the membrane-filter enrichment technique, were characterized. Analysis of their 16S rRNA gene sequence grouped strains ND5 and MY14^T within the family Oxalobacteraceae (Betaproteobacteria). The highest pairwise sequence similarities for strain ND5 were found with members of the genus Herminiimonas, namely with Herminiimonas saxobsidens NS11^T (99.8%) and Herminiimonas glaciei UMB49^T (99.6%). Although some fatty acid profiles, physiological and biochemical differences exist between strain ND5 and the respective Herminiimonas-type strains, DNA–DNA hybridization experiments confirm that strain ND5 is a member of the H. glaciei genospecies. Taxonomical analyses revealed a wider range of variability within this genus than considered previously. The highest pairwise nucleotide similarity for strain MY14^T was found with Oxalicibacterium flavum (96.8%). Phylogenetic analyses based on 16S rRNA and cpn60 gene sequences, DNA–DNA hybridization, fatty acid profiles, physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain MY14^T from other Oxalicibacterium species representing a new species, for which the name Oxalicibacterium solurbis sp. nov. (type strain MY14^T=NBRC 102665^T,=CCM 7664^T) is proposed.