Antarcticirhabdus aurantiaca gen. nov., sp. nov., isolated from Antarctic gravel soil.

ABSTRACT

Strain R10T was isolated from a gravel soil sample obtained from Deception Island, Antarctica. The isolate was a Gram-stain-negative, strictly aerobic, motile, short-rod-shaped bacterium, and its colonies were orange yellow in colour. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain R10T belonged to the family Aurantimonadaceae and shared highest sequence similarity with Jiella aquimaris LZB041T (96.3 % sequence similarity), Aurantimonas aggregata R14M6T (96.0 %) and Aureimonas frigidaquae JCM 14755T (96.0 %). Phylogenetic analysis showed that strain R10T affiliated with members of the family Aurantimonadaceae and represented an independent lineage. Growth occurred at 10-37 °C (optimum, 28-32 °C), up to 1.0 % (w/v) NaCl (optimum, 0 %) and pH 5.5-9.0 (optimum, pH 7.0). The major respiratory quinone of strain R10T was Q-10. Its major fatty acids were C18  1 ω7c and C16 0. The polar lipid profile of strain R10T comprised diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, two unknown phospholipids and two unknown aminophospholipids. The genome of strain R10T was 5.92 Mbp with a G+C content of 69.1 % based on total genome calculations. Average nucleotide identity (ANI) values between R10T and other related species of the family Aurantimonadaceae were found to be low (ANIm <87.0 %, ANIb <75.0 % and OrthoANIu <77.0 %). Furthermore, digital DNA-DNA hybridization (dDDH) and average amino acid identity (AAI) values between strain R10T and the closely related species ranged from 19.5-20.6% and from 60.6-64.0 %, respectively. Based on the results of our phylogenetic, phenotypic, genotypic and chemotaxonomic analyses, it is concluded that strain R10T represents a novel genus and species of the family Aurantimonadaceae, for which the name Antarcticirhabdus aurantiaca gen. nov., sp. nov. is proposed. The type strain is R10T (=KCTC 72466T=CGMCC 1.17155T).