physiological and genomic traits for arsenite-oxidizing bacteria. AS8

Strain AS8 was isolated from a heavy-metal contaminated soil in Daegu and represents a novel species which has a capability for arsenic oxidation belonging to the Herminiimonas. The strain can be grown heterotrophically. Cells of strain AS8 were rod and stained Gram-stain-negative, and formed small beige-pigmented colonies. Strain AS8 grew in the range of 20–40 °C (optimum 25–30 °C), pH 3.0–9.0 (optimum 5.0–6.0), and 0–1% NaCl (w/v, optimum 0.2–0.4%). Under chemolithoheterotrophic growing, the strain utilized limited organic acids and amino acids as the carbon and/or nitrogen sources but not the electron sources. However, unexpectedly, most carbohydrates did not support growth as a sole carbon sources. Moreover, the result was supported by genomic traits lacking most ABC transporters related to oligo/monosaccharide in the AS8 genome. AS8 genome has the gene sets for colonization, flagella biosynthesis, urea degradation, and several heavy-metal and antibiotics resistance. Here, we show for the first time that the isolate could grow sulfur oxidation on the complex medium (i.e. TSA). Comparative genomics with some of the Herminiimonas and related genome sequences, strain AS8 reveal that most genes had higher relatives to the Janthinobacterium sp. Marseille (ca. 65.8%) than Herminiimona spp. (ca. 14.3%). It is also supported by global alignment analysis (i.e. Dot plotting) between genome sequences of the references and relatives. Surprisingly, we identified prophage-related sequences (about 38kb length) located in genome with integrase, recombinase, and phage morphogenesis proteins. Finally, based on polyphasic and genomic analyses, we describe a novel species of the genus Herminiimonas, represented by strain AS8T, for which we propose the name Herminiimonas arsenitoxidans sp. nov.