Nisaea sediminum sp. nov., a heavy metal resistant bacterium isolated from marine sediment in the East China Sea

A Gram-negative, rod-shaped, motile and strictly aerobic bacterium, designated NBU1469(T), was isolated from marine sediment sampled on Meishan Island located in the East China Sea. Strain NBU1469(T) grew optimally at temperature of 40 degrees C, NaCl concentration of 2.0% (w/v) and pH 7.5. Catalase and oxidase activities, H2S production, nitrate reduction and hydrolysis of Tween 20 were positive. Indole, methyl red reaction, urease, hydrolysis of gelatin, starch, casein, Tweens 40, 60 and 80 were negative. The major cellular fatty acids were C-16:0, C-19:0 cyclo omega 8c and summed feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c). The only respiratory quinone was ubiquinone-10 (Q-10). The major polar lipids were phosphatidylglycerol, two unidentified amino-phospholipids and two unidentified phospholipids. Comparative analysis of the 16S rRNA gene sequence showed highest similarities to the species with validated name Nisaea nitritireducens DR41_18(T) (98.1%) and Nisaea denitrificans DR41_21(T) (97.6%). Phylogenetic analyses indicated that strain NBU1469(T) formed a distinct lineage with strains Nisaea nitritireducens DR41_18(T) and Nisaea denitrificans DR41_21(T) within the genus Nisaea. The average nucleotide identity and digital DNA-DNA hybridization values between strain NBU1469(T) and related species of genus Nisaea were well below the threshold limit for prokaryotic species delineation. The DNA G + C content was 63.6%. Based on its phenotypic, chemotaxonomic and genotypic data, strain NBU1469(T) is considered to be a representative of a novel species in the genus Nisaea, for which the name Nisaea sediminum sp. nov. is proposed. The type strain is NBU1469(T) (=KCTC 82224( T) =MCCC 1K04763(T)).