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, YPL8(T), SLN56(T), LT61(T) and KZCA68(T), 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 YPL8(T), SLN56(T), LT61(T) and the current members of Natrinema were 94.1-98.2% and 89.3-95.1%, respectively, while these values among strain KZCA68(T) 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 YPL8(T) contained phosphatidic acid (PA), phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), sulfated mannosyl glucosyl diether (S-DGD-1), disulfated mannosyl glucosyl diether (S 2-DGD) and sulfated mannosyl glucosyl diether-phosphatidic acid (S-DGD-PA). Strain SLN56(T) contained PA, PG, phosphatidylglycerol sulphate (PGS), PGP-Me, S-DGD-1, S 2-DGD and S-DGD-PA. Strain LT61(T) contained PA, PG, PGS, PGP-Me, S-DGD-1 and S 2-DGD. The phospholipids of strain KZCA68(T) were PA, PG and PGP-Me. These results showed that strains YPL8(T) (=CGMCC 1.13883(T)=JCM 31181(T)), SLN56(T) (=CGMCC 1.14945T=JCM 30832(T)) and LT61(T) (=CGMCC 1.14942(T)=JCM 30668(T)) 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 KZCA68(T) (=CGMCC 1.17211(T)=JCM 34158(T)) represents a novel species of Haloterrigena, for which the name Haloterrigena alkaliphila sp. nov. is proposed.

Automated summary

Four halophilic archaeal strains, YPL8(T), SLN56(T), LT61(T), and KZCA68(T), were isolated from different regions in China. Three of these strains belong to a new species of the genus Natrinema, named Natrinema halophilum sp. nov., Natrinema salinisoli sp. nov., and Natrinema amylolyticum sp. nov. The fourth strain is a new species of the genus Haloterrigena, named Haloterrigena alkaliphila sp. nov.