Halomonas piezotolerans sp. nov., a multiple-stress-tolerant bacterium isolated from a deep-sea sediment sample of the New Britain Trench

A piezotolerant, H2O2-tolerant, heavy-metal-tolerant, slightly halophilic bacterium (strain NBT06E8(T)) 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 degrees C (optimum, 30 degrees 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 H2O2. Resuls of 16S rRNA gene sequence analysis showed that strain NBT06E8(T) is closely related to Halomonas aquamarina DSM 30161(T) (99.5%), Halomonas meridiana DSM 5425(T) (99.43%) and Halomonas axialensis Althf1(T) (99.35%). The digital DNA-DNA hybridization values between strain NBT06E8(T) 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 NBT06E8(T) 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 omega7c and/or C18 : 1 omega6c) and C16 : 0. The predominant respiratory quinone detected was ubiquinone-9 (Q-9). Based on its phenotypic and phylogenetic characteristics, we conclude that strain NBT06E8(T) represents a novel species of the genus Halomonas, for which the name Halomonas piezotolerans sp. nov. is proposed (type strain NBT06E8(T)= MCCC 1K04228(T)=KCTC 72680(T)).