Isoptericola maris sp. nov., a novel actinobacterium isolated from the marine sediment in the Bohai Sea, China.

A Gram-staining positive, greenish-yellow, immotile, catalase-positive, oxidase-negative actinobacterium, designated strain G70T, was isolated from the marine sediment in the Bohai Sea, China. The results of phylogenetic analysis based on the 16S rRNA gene sequences indicated that the strain G70T belongs to the genus Isoptericola, revealing 99.1% similarity to Isoptericola halotolerans YIM 70177T, 98.7% similarity to Isoptericola chiayiensis 06182 M-1T and 98.2% similarity to Isoptericola salitolerans TRM F109T. Strain G70T grew at 4-45 °C (optimum 30 °C), pH 6-13 (optimum 8-9) and 0-25% (wt/v) NaCl (optimum 1%). The genome size of strain G70T was 3.59 Mb, with DNA G+C content of 72.6 mol%. Average nucleotide identities between strain G70T and I. halotolerans YIM 70177T and I. chiayiensis 06182 M-1T were 83.6 and 80.7%, respectively. The digital DNA-DNA hybridization values among I. halotolerans YIM 70177T and I. chiayiensis 06182 M-1T are 26.5 and 23.0%, respectively. The predominant fatty acids (>10%) of strain G70T were anteiso-C15 : 0 and C16 : 0, and the respiratory quinones were MK-9 (H4), MK-9 (H2) and MK-9. The polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, an unknown phosphoglycolipid and an unknown phospholipid. Strain G70T showed significant broad-spectrum antimicrobial activity against both Gram-staining-negative and Gram-staining-positive bacteria and fungi. Based on all these phenotypic, genotypic and phylogenetic results, strain G70T was distinguished from other species with validly published names in the genus Isoptericola and should be classified as representing a novel species, for which the name Isoptericola maris sp. nov. was proposed. The type strain is G70T (MCCC 1K08870T=KCTC 59000T).