Hymenobacter caeli sp. nov., an airborne bacterium isolated from King George Island, Antarctica

Abstract

A rod-shaped and Gram-stain-negative bacterial strain 9A^T, was isolated from an air sample collected at King George Island, maritime Antarctica. Phylogenetic analysis based on 16S rRNA gene sequence reveals that strain 9A^T belongs to the genus Hymenobacter and shows the highest similarity to Hymenobacter coccineus CCM 8649^T (96.8 %). The DNA G+C content based on the draft genome sequence is 64.9 mol%. Strain 9A^T is strictly aerobic, psychrophilic, catalase-positive, oxidase-positive and non-motile. Growth is observed at 0-20 °C (optimum 10 °C), pH 6.0-8.0 (optimum pH 7.0), and in the absence of NaCl. The predominant menaquinone of strain 9A^T is MK-7 and the major fatty acids comprise Summed Feature 3 (C_{16 : 1} ω7c and/or C_{16 : 1} ω6c; 25.2 %), iso-C_{15 : 0} (23.2 %), C_{16 : 1} ω5c (11.6 %), Summed Feature 4 (anteiso-C_{17 : 1} B/iso-C_{17 : 1} I) (9.6 %) and anteiso-C_{15 : 0} (9.6 %). The polar lipid profile consists of the major lipid phosphatidylethanolamine and moderate to minor amounts of phosphatidylserine, unidentified aminolipids, aminophospholipids, aminophosphoglycolipids, polar lipids lacking a functional group and an unidentified phospholipid and a glycolipid. In the polyamine pattern sym-homospermidine is predominant. On the basis of the results obtained, strain 9A^T is proposed as a novel species of the genus Hymenobacter, for which the name Hymenobacter caeli sp. nov. is suggested. The type strain is 9A^T (=CCM 8971^T=LMG 32109^T=DSM 111653^T).

Keywords: Hymenobacter sp.; airborne bacteria; extremophiles; maritime Antarctica; psychrophiles.