Natrinema halophilum sp. nov., Natrinema salinisoli sp. nov., Natrinema amylolyticum sp. nov. and Haloterrigena alkaliphila sp. nov., four extremely halophilic archaea isolated from salt mine, saline soil and salt lake

Four halophilic archaeal strains, YPL8T, SLN56T, LT61T and KZCA68T, were isolated from a salt mine, saline soil and a salt lake located in different regions of China. Sequence similarities of 16S rRNA and rpoB' genes among strains YPL8T, SLN56T, LT61T and the current members of Natrinema were 94.1-98.2 % and 89.3-95.1 %, respectively, while these values among strain KZCA68T and the current members of Haloterrigena were 97.2-97.4 % and 91.7-91.9 %, respectively. The average nucleotide identity, in silico DNA-DNA hybridization and average amino acid identity values among these four strains and their closely related species were all lower than the threshold values for species boundary. All four strains were unable to hydrolyse casein, gelatin, or Tween 80. Strain YPL8T contained phosphatidic acid (PA), phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), sulfated mannosyl glucosyl diether (S-DGD-1), disulfated mannosyl glucosyl diether (S2-DGD) and sulfated mannosyl glucosyl diether-phosphatidic acid (S-DGD-PA). Strain SLN56T contained PA, PG, phosphatidylglycerol sulphate (PGS), PGP-Me, S-DGD-1, S2-DGD and S-DGD-PA. Strain LT61T contained PA, PG, PGS, PGP-Me, S-DGD-1 and S2-DGD. The phospholipids of strain KZCA68T were PA, PG and PGP-Me. These results showed that strains YPL8T (=CGMCC 1.13883T=JCM 31181T), SLN56T (=CGMCC 1.14945T=JCM 30832T) and LT61T (=CGMCC 1.14942T=JCM 30668T) represent novel species of the genus Natrinema, for which the names, Natrinema halophilum sp. nov., Natrinema salinisoli sp. nov. and Natrinema amylolyticum sp. nov. are proposed. Strain KZCA68T (=CGMCC 1.17211T=JCM 34158T) represents a novel species of Haloterrigena, for which the name Haloterrigena alkaliphila sp. nov. is proposed.