Profundirhabdus halotolerans gen. nov., sp. nov., an haloalkaliphilic actinobacterium isolated from seawater of the Mariana Trench

Abstract

A Gram-stain-positive, strictly aerobic, rod-shaped actinobacterium, designated strain ZYF776T, was isolated from seawater of the Mariana Trench collected at a depth of 4000 m. Results of 16S rRNA gene sequence analysis indicated that strain ZYF776Twas a member of the classNitriliruptoriaand closely related toNitriliruptor alkaliphilusDSM 45188T(member of the orderNitriliruptorales, 94.94 % sequence similarity) andEgicoccus halophilusKCTC 33612T(member of the orderEgicoccales, 94.46 %). Strain ZYF776Twas catalase-positive and oxidase-negative. Growth occurred at 16–37 °C (optimum, 28 °C), in the presence of 0–13 % NaCl (w/v; optimum, 4 %) and at pH 7.0–10.0 (optimum, pH 8.0). Cell-wall hydrolysates of strain ZYF776Tcontainedmeso-diaminopimelic (peptidoglycan type A1γ), with ribose, rhamnose and a smaller amount of xylose as the cell-wall sugars. The major menaquinone was MK-10. The predominant fatty acids (>10 %) were C16:0, C17:1ω8cand summed feature 3 (C16 : 1ω7cand/or C16 : 1ω6c). The polar lipid profile mainly contained diphosphatidylglycerol, phosphatidylglycerol and phosphoglycolipid. The genomic DNA G+C content of strain ZYF776Twas 68.7 mol%. The genome of strain ZYF776Twas about 5.61 Mbp in size, which was larger than those of the reference strainsN. alkaliphilusDSM45188T(5.56 Mbp) andE. halophilusKCTC 33612T(3.98 Mbp). The average nucleotide identity and digital DNA–DNA hybridization values between ZYF776Tand the related strainsN. alkaliphilusDSM 45188TandE. halophilusKCTC 33612Twere 76.7 and 20.3 % and 75.8 and 20.0 %, respectively. Based on the polyphasic evidence, a novel genus and species with the nameProfundirhabdus halotoleransgen. nov., sp. nov. is proposed. The type strain is ZYF776T(=JCM 33008T=MCCC 1K03555T).