Kaistella polysaccharea sp. nov., isolated from Antarctic intertidal sediment produces a novel extracellular...

An exopolysaccharide-producing bacterial strain GW4-15^T, belonging to the genus Kaistella, was isolated from intertidal sediment from King George Island, Antarctic. The strain was Gram-stain-negative, aerobic, rod-shaped, non-motile and yellow-pigmented. The strain was able to grow in the presence of 0-2 % (w/v) NaCl (optimum, 0 %), at 4-30 °C (optimum, 20-28 °C) and at pH 5.0-10.0 (optimum, pH 8.0). A phylogenetic tree based on 16S rRNA gene sequences showed that strain GW4-15^T formed a lineage within the genus Kaistella with the closest phylogenetic neighbours Kaistella carnis NCTC 13525^T (98.3 %), Kaistella gelatinilytica G5-32^T (97.7 %), Kaistella antarctica LMG 24720^T (97.4 %) and Kaistella yonginensis HMD1043^T (96.9 %). Digital DNA-DNA hybridization values of strain GW4-15^T with K. carnis NCTC 13525^T, K. antarctica LMG 24720^T, K. gelatinilytica G5-32^T and K. yonginensis HMD1043^T were 22.8, 22.0, 21.7 and 21.6 %, respectively. The average nucleotide identity values between strain GW4-15^T and K. carnis NCTC 13525^T , K. antarctica LMG 24720^T, K. gelatinilytica G5-32^T and K. yonginensis HMD1043^T were 79.3, 78.6, 77.5 and 77.2 %, respectively. The G+C content of the genome was 36.2 mol%. The major phospholipids were phosphatidylethanolamine and aminophospholipid. The predominant menaquinone was MK-6. The major fatty acids were anteiso-C_15 : 0 (28.7 %), iso-C_16 : 0 3-OH (15.7 %), iso-C_16 : 0 H (10.0 %), iso-C_16 : 0 (5.4 %), summed feature 9 (comprising iso-C_17 : 1  ω9c and/or 10-methyl C_16 : 0; 5.2 %) and iso-C_15 : 0 (5.1 %). The monosaccharide composition of the new type of extracellular polymeric of GW4-15^T was Glc, GalN, GlcN, Rha, Man and Gal with a molar ratio of 3.14 : 3.83 : 8.38 : 5.16 : 1 : 2.82. Based on phenotypic, phylogenetic and genotypic data, a novel species, Kaistella polysaccharea sp. nov., is proposed with the type strain GW4-15^T (=CGMCC 1.19368^T=KCTC 92753^T).