Phylogenetic analyses of the genus Glaciecola: emended description of the genus Glaciecola, transfer of Glaciecola mesophila, G. agarilytica, G. aquimarina, G. arctica, G. chathamensis, G. polaris and G. psychrophila to the genus Paraglaciecola gen. nov.

Phylogenetic analyses of the genusGlaciecolawere performed using the sequences of the 16S rRNA gene and the GyrB protein to establish its taxonomic status. The results indicated a consistent clustering of the genusGlaciecolainto two clades, with significant bootstrap values, with all the phylogenetic methods employed. Clade 1 was represented by seven species,Glaciecola agarilytica,G. aquimarina,G. arctica,G. chathamensis,G. mesophila,G. polarisandG. psychrophila, while clade 2 consisted of only three species,Glaciecola nitratireducens,G. pallidulaandG. punicea. Evolutionary distances between species of clades 1 and 2, based on 16S rRNA gene and GyrB protein sequences, ranged from 93.0 to 95.0 % and 69.0 to 73.0 %, respectively. In addition, clades 1 and 2 possessed 18 unique signature nucleotides, at positions 132, 184 : 193, 185 : 192, 230, 616 : 624, 631, 632, 633, 738, 829, 1257, 1265, 1281, 1356 and 1366, in the 16S rRNA gene sequence and can be differentiated by the occurrence of a 15 nt signature motif 5′-CAAATCAGAATGTTG at positions 1354–1368 in members of clade 2. Robust clustering of the genusGlaciecolainto two clades based on analysis of 16S rRNA gene and GyrB protein sequences, 16S rRNA gene sequence similarity of ≤95.0 % and the occurrence of signature nucleotides and signature motifs in the 16S rRNA gene suggested that the genus should be split into two genera. The genusParaglaciecolagen. nov. is therefore created to accommodate the seven species of clade 1, while the nameGlaciecolasensu strictois retained to represent species of clade 2. The species of clade 1 are transferred to the genusParaglaciecolaasParaglaciecola mesophilacomb. nov. (type strain DSM 15026T = KMM 241T),P. agarilyticacomb. nov. (type strain NO2T = KCTC 12755T = LMG 23762T),P. aquimarinacomb. nov. (type strain GGW-M5T = KCTC 32108T = CCUG 62918T),P. arcticacomb. nov. (type strain BSs20135T = CCTCC AB 209161T = KACC 14537T),P. chathamensiscomb. nov. (type strain E3T = CGMCC 1.7001T = JCM 15139T),P. polariscomb. nov. (type strain ARK 150T = CIP 108324T = LMG 21857T) andP. psychrophilacomb. nov. (type strain 170T = CGMCC1.6130T = JCM 13954T). The type species of the genusParaglaciecolaisParaglaciecola mesophila. An emended description of the genusGlaciecolais provided. In addition, a novel strain, 162Z-12T, was isolated from seawater collected as part of an iron fertilization experiment (LOHAFEX) conducted in the Southern Ocean in 2009 and was subjected to polyphasic taxonomic characterization. Cells of 162Z-12Twere Gram-negative, aerobic, motile, ovoid to short rod-shaped, obligatorily halophilic and possessed all the characteristics of the genusParaglaciecola. Strain 162Z-12Tshared the highest 16S rRNA gene sequence similarity with the type strains ofP.agarilytica(99.7 %),P.chathamensis(99.7 %),P.mesophila(98.5 %) andP.polaris(98.3 %). However, it exhibited DNA–DNA relatedness of less than 70.0 % with its nearest phylogenetic relatives, well below the threshold value for species delineation. Further, strain 162Z-12Tdiffered from the nearest species in several phenotypic characteristics, in addition to the occurrence of unique nucleotides G, T, T and T at positions 1194, 1269, 1270 and 1271 of the 16S rRNA gene. Based on the cumulative differences it exhibited from its nearest phylogenetic neighbours, strain 162Z-12Twas identified as a novel member of the genusParaglaciecolaand assigned to the novel speciesParaglaciecola oceanifecundanssp. nov. The type strain ofParaglaciecola oceanifecundansis 162Z-12T( = KCTC 32337T = LMG 27453T).