Halomonas piezotolerans sp. Nov., a multiple-stress-tolerant bacterium isolated from a deep-sea sediment sample of the new britain trench

Abstract

A piezotolerant, H2 O2-tolerant, heavy-metal-tolerant, slightly halophilic bacterium (strain NBT06E8T) was isolated from a deep-sea sediment sample collected from the New Britain Trench at depth of 8900 m. The strain was aerobic, motile, Gram-stain-negative, rod-shaped, oxidase-positive and catalase-positive. Growth of the strain was observed at 4–45 °C (optimum, 30 °C), at pH 5–11 (optimum, pH 8–9) and in 0.5–21 % (w/v) NaCl (optimum, 3–7 %). The optimum pressure for growth was 0.1–30 MPa with tolerance up to 60 MPa. Under optimum growth conditions, the strain could tolerate 15 mM H2 O2 . Resuls of 16S rRNA gene sequence analysis showed that strain NBT06E8T is closely related to Halomonas aquamarina DSM 30161T (99.5%), Halomonas meridiana DSM 5425T (99.43%) and Halomonas axialensis Althf1T (99.35%). The digital DNA–DNA hybridization values between strain NBT06E8T and the three related type strains, H. aquamarina, H. meridiana and H. axialensis, were 30.5±2.4 %, 30.7±2.5% and 31.5±2.5 %, respectively. The average nucleotide identity values between strain NBT06E8T and the three related type strains were 86.26, 86.26 and 83.63 %, respectively. The major fatty acids were summed feature 8 (C18: 1 ω7c and/or C18: 1 ω6c) and C16: 0 . The predominant respiratory quinone detected was ubiquinone-9 (Q-9). Based on its phenotypic and phylogenetic character-istics, we conclude that strain NBT06E8T represents a novel species of the genus Halomonas, for which the name Halomonas piezotolerans sp. nov. is proposed (type strain NBT06E8T= MCCC 1K04228T=KCTC 72680T).