Phenylobacterium glaciei sp. nov., isolated from Vestrebroggerbreen, a valley glacier in Svalbard, Arctic

Abstract

A Gram-stain-negative, rod-shaped bacterial strain designated as 20VBR1^T was isolated from a valley glacier (Vestrebroggerbreen) snout ice sample from Ny-Ålesund, Svalbard, Arctic. The colonies were smooth, circular and light creamish on half-strength R2A agar and grew at 10-35 °C (optimum, 20 °C), at pH 6.5-8.0 (optimum, 7.0) and with 0-2.5 % (w/v) NaCl (optimum, 0.5 %). 16S rRNA gene sequence analysis revealed that strain 20VBR1^T belonged to the genus Phenylobacterium and was most closely affiliated to Phenylobacterium aquaticum W2-3-4^T (97.65 % similarity), Phenylobacterium haematophilum LMG 11050^T (97.57 %) and Phenylobacterium koreense Slu-01^T (96.91 %). 20VBR1^T has a genome size of 4.24 Mb, comprising 4185 predicted genes with a DNA G+C content of 67.86 mol%. DNA-DNA hybridization experiments indicated that the DNA-DNA relatedness between strain 20VBR1^T and P. aquaticum KACC 18306^T was 41.95±4.36 %, well below the threshold (<70 %) to delineate bacterial species. Genome relatedness indexes revealed that the average nucleotide identity and digital DNA-DNA hybridization values between 20VBR1^T and its closest phylogenomic relative, P. aquaticum KACC 18306^T, were 78.97 and 22.10 %, respectively. The predominant isoprenoid quinone was ubiquinone (Q-10) and the major polar lipids were phosphatidylglycerol, one unknown phospholipid, one unknown glycolipid and four unidentified polar lipids. The major fatty acids (>10 %) of strain 20VBR1^T were summed feature 8 (comprising C_{18 : 1} ω7c and/or C_{18 : 1} ω6c), summed feature 3 (comprising C_{16 : 1} ω6c and/or C_{16 : 1} ω7c) and C_{16 : 0}. Based on the physiological, biochemical, chemotaxonomic, phylogenetic and phylogenomic analyses, isolate 20VBR1^T is considered to represent a novel species of the genus Phenylobacterium, for which the name Phenylobacterium glaciei sp. nov. is proposed. The type strain is 20VBR1^T (=JCM 33227 ^T=DSM 111428 ^T=MCC 4220 ^T).

Keywords: Arctic; Phenylobacterium; Svalbard; snout ice; valley glacier.