Tardiphaga alba sp. nov., a heavy- metal- tolerant bacterium isolated from garden soil

A previously undescribed, heavy- metal- tolerant, motile, Gram- negative bacterium, designated strain SK50- 23T, was characterized using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SK50- 23T was closely related to Tardiphaga robiniae LMG 26467T and the non- phototrophic 'Rhodopseudomonas boonkerdii' NS23T (98.1 and 97.3 % 16S rRNA gene sequence similarity, respectively). Strain SK50- 23T possessed a circular genome of 5.86 Mb, with a DNA G+C content of 61.9 mol%. Digital DNA-DNA hybridization showed 20.8-21.6 % similarity between strain SK50- 23T and related species. In addition, the whole- genome average nucleotide identity values between strain SK50- 23T and related species ranged from 75.1 to 83.5 %. The major cellular fatty acid identified in strain SK50- 23T was C18:1 omega 7c, and the main isoprenoid quinone present was ubiquinone Q- 10. Strain SK50- 23T could be assigned to the genus Tardiphaga with the species name Tardiphaga alba sp. nov. based on morphological, chemotaxonomic and genome- based taxonomic characteristics, and 16S rRNA gene - based phylogenetic characteristics. The type strain of the proposed novel species is SK50- 23T (=NBRC 108825T=CGMCC No. 1.12037T).