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 G70 T , 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 G70 T belongs to the genus Isoptericola , revealing 99.1% similarity to Isoptericola halotolerans YIM 70177 T , 98.7% similarity to Isoptericola chiayiensis 06182 M-1 T and 98.2% similarity to Isoptericola salitolerans TRM F109 T . Strain G70 T 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 G70 T was 3.59 Mb, with DNA G+C content of 72.6 mol%. Average nucleotide identities between strain G70 T and I. halotolerans YIM 70177 T and I. chiayiensis 06182 M-1 T were 83.6 and 80.7%, respectively. The digital DNA–DNA hybridization values among I. halotolerans YIM 70177 T and I. chiayiensis 06182 M-1 T are 26.5 and 23.0%, respectively. The predominant fatty acids (>10%) of strain G70 T were anteiso-C 15 : 0 and C 16 : 0 , and the respiratory quinones were MK-9 (H 4 ), MK-9 (H 2 ) and MK-9. The polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, an unknown phosphoglycolipid and an unknown phospholipid. Strain G70 T 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 G70 T 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 G70 T (MCCC 1K08870 T =KCTC 59000 T ).