Halostella pelagica sp. nov. and Halostella litorea sp. nov., isolated from salted brown alga Laminaria

Genome-based taxonomy of genera Haloarcula and Halomicroarcula, and description of six novel species of Haloarcula

The genera Haloarcula and Halomicroarcula are the most closely related genera within the family Haloarculaceae (class Halobacteria). The respective 16S rRNA genes of type strains from the genus Haloarcula showed 94.7-96.5% similarities to their homologous genes of type strains from the genus Halomicroarcula. The Haloarcula species showed 89.3-92.8% rpoB' gene similarities to Halomicroarcula species. These similarities were higher than the proposed genus boundary. Phylogenomic analysis revealed that these two genera formed a tight cluster separated from Halomicrobium with high bootstrap confidence. The average amino acid identity (AAI) values among Haloarcula and Halomicroarcula were 70.1-74.5%, higher than the cutoff value (67.0%) to differentiate the genera Haloarcula and Halomicroarcula from Halomicrobium. These results indicated that the genus Halomicroarcula should be merged with Haloarcula. Then, six novel species are described based on strains DFY41T, GDY20T, SHR3T, XH51T, YJ-61-ST, and ZS-22-S1T isolated from coarse sea salt, marine solar saltern, and salt lake (China). These six strains formed separate clades (90.1-99.3% 16S rRNA and 89.0-94.9% rpoB' gene similarities) and then clustered with current Haloarcula and Halomicroarcula species (89.4-99.1% 16S rRNA and 87.6-95.0% rpoB' gene similarities), as revealed by phylogenetic analyses. The average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH), and AAI values among these six strains and current Haloarcula and Halomicroarcula species were 76.2-89.8%, 25.3-46.0%, and 70.3-89.7%, respectively, clearly below the species demarcation threshold. These six strains were distinguished from current Haloarcula and Halomicroarcula species according to differential phenotypic characteristics. Six novel species, Haloarcula halophila sp. nov., Haloarcula litorea sp. nov., Haloarcula rara sp. nov., Haloarcula halobia sp. nov., Haloarcula pelagica sp. nov., and Haloarcula ordinaria sp. nov., are proposed to accommodate strains DFY41T, GDY20T, SHR3T, XH51T, YJ-61-ST, and ZS-22-S1T, respectively.

Salinigranum marinum sp. nov. and Halohasta salina sp. nov., halophilic archaea isolated from sediment of a marine saltern and inland saline soil

Two halophilic archaeal strains, ZS-10T and GSL13T, were isolated from the Zhoushan marine saltern in Zhejiang, and an inland saline soil from the Tarim Basin, Xinjiang, PR China, respectively. The cells of strain ZS-10T were pleomorphic while those of strain GSL13T were rod-shaped. Both of them stained Gram-negative and formed red-pigmented colonies on agar plates and their cells lysed in distilled water. The optimum growth of strain ZS-10T was observed at 40 °C, 3.4 M NaCl, 0.03 M MgCl2 and pH 7.5, while that of strain GSL13T was at 37 °C, 3.1 M NaCl, 0.5 M MgCl2 and pH 7.5. Phylogenetic and phylogenomic analyses indicated that these two strains were related to Salinigranum and Halohasta, respectively. Strains ZS-10T and GSL13T could be differentiated from the current members of Salinigranum and Halohasta based on the comparison of diverse phenotypic characteristics. The average amino acid identity, average nucleotide identity and digital DNA-DNA hybridization values among strain ZS-10T and current species of Salinigranum were 75.8-78.6 %, 80.6-81.9 % and 24.3-26.1 %, respectively. These values between strain GSL13T and current species of Halohasta were 78.4-80.8 %, 79.8-82.8% and 22.7-25.7 %, respectively, clearly below the threshold values for species demarcation. The polar lipids of strain ZS-10T were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me) and sulphated mannosyl glucosyl diether (S-DGD-1), while those of strain GSL13T were phosphatidic acid, PG, PGP-Me, phosphatidylglycerol sulphate and S-DGD-1. The polar lipid profile of strain GSL13T was identical to those of Halohasta, whereas strain ZS-10T did not contain the minor glycolipids detected in the current Salinigranum species. The phenotypic, phylogenetic and genome-based results suggested that strains ZS-10T (=CGMCC 1.12868T=JCM 30241T) and GSL13T (=CGMCC 1.15214T=JCM 30841T) represent two novel species, for which the names Salinigranum marinum sp. nov. and Halohasta salina sp. nov. are proposed.

Halomicroarcula laminariae sp. nov. and Halomicroarcula marina sp. nov., extremely halophilic archaea isolated from salted brown alga Laminaria and coastal saline-alkali lands

Four extremely halophilic archaeal strains, LYG-108T, LYG-24, DT1T and YSSS71, were isolated from salted Laminaria produced in Lianyungang and saline soil from the coastal beach at Jiangsu, PR China. The four strains were found to be related to the current species of Halomicroarcula (showing 88.1-98.5% and 89.3-93.6% similarities, respectively) as revealed by phylogenetic analysis based on 16S rRNA and rpoB' genes. These phylogenies were fully supported by the phylogenomic analysis, and the overall genome-related indexes (average nucleotide identity, DNA-DNA hybridization and average amino acid identity) among these four strains and the Halomicroarcula species were 77-84 %, 23-30 % and 71-83 %, respectively, clearly below the threshold values for species demarcation. Additionally, the phylogenomic and comparative genomic analyses revealed that Halomicroarcula salina YGH18T is related to the current species of Haloarcula rather than those of Halomicroarcula, Haloarcula salaria Namwong et al. 2011 is a later heterotypic synonym of Haloarcula argentinensis Ihara et al. 1997, and Haloarcula quadrata Oren et al. 1999 is a later heterotypic synonym of Haloarcula marismortui Oren et al. 1990. The major polar lipids of strains LYG-108T, LYG-24, DT1T and YSSS71 were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulphate, sulphated mannosyl glucosyl diether and additional glycosyl-cardiolipins. All these results showed that strains LYG-108T (=CGMCC 1.13607T=JCM 32950T) and LYG-24 (=CGMCC 1.13605=JCM 32949) represent a new species of the genus Halomicroarcula, for which the name Halomicroarcula laminariae sp. nov. is proposed; strains DT1T (=CGMCC 1.18928T=JCM 35414T) and YSSS71 (=CGMCC 1.18783=JCM 34915) also represent a new species of the genus Halomicroarcula, for which the name Halomicroarcula marina sp. nov. is proposed.

Halocatena salina sp. nov., a filamentous halophilic archaeon isolated from Aiding Salt Lake

A filamentous cell-shaped halophilic archaeon (strain AD-1^T) was isolated from Aiding Salt Lake, PR China. Its colonies on HCM7 agar plates were pinkish white, 1-4 mm (diameter), elevated and round. The optimum conditions for growth were observed at 42 °C, 4.3 M NaCl, 0.01 M MgCl₂ and pH 7. Strain AD-1^T could hydrolyse Tween 60, Tween 80, starch and gelatin. Phylogenetic analysis based on 16S rRNA gene, rpoB' and the concatenated 484 single-copy orthologous proteins revealed that strain AD-1^T formed a clade with Halocatena pleomorpha SPP-AMP-1^T. The average nucleotide identity and in silico DNA-DNA hybridization values between strain AD-1^T and Halocatena pleomorpha SPP-AMP-1^T were both below the species delineation thresholds (95~96 and 70 %, respectively). The major phospholipids of strain AD-1^T were phosphatidic acid, phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester, while the major glycolipids were sulphated galactosyl mannosyl glucosyl diether, galactosyl mannosyl glucosyl diether and glucosyl mannosyl glucosyl diether. The phenotypic, phylogenetic and genome-based analyses suggested that strain AD-1^T (=CGMCC 1.13724^T=JCM 32960^T) represents a novel species, for which the name Halocatena salina sp. nov. is proposed.

Halorussus vallis sp. nov., Halorussus aquaticus sp. nov., Halorussus gelatinilyticus sp. nov., Halorussus limi sp. nov., Halorussus salilacus sp. nov., Halorussus salinisoli sp. nov.: six extremely halophilic archaea isolated from solar saltern, salt lake and saline soil

Six novel halophilic archaeal strains of XZYJT10^T, XZYJ18^T, XZYJT40^T, XZYJT49^T, YCN54^T and LT46^T were isolated from a solar saltern in Tibet, a salt lake in Shanxi, and a saline soil in Xinjiang, China. Sequence similarities of 16S rRNA and rpoB' genes among strains XZYJT10^T, XZYJ18^T, XZYJT40^T, XZYJT49^T, YCN54^T, LT46^T and current members of Halorussus were 90.6-97.8% and 87.8-96.4%, respectively. The average nucleotide identity and in silico DNA-DNA hybridization values among these six strains and current Halorussus members were in the range of 76.5-87.5% and 21.0-33.8%, respectively. These values were all below the species boundary threshold values. The phylogenomic tree based on 122 conserved archaeal protein marker genes revealed that the six novel strains formed individual distinct branches and clustered tightly with Halorussus members. Several phenotypic characteristics distinguished the six strains from current Halorussus members. Polar lipid analysis showed that the six novel strains contained phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and two to three glycolipids. Phenotypic, chemotaxonomic and phylogenetic properties showed that the six strains represented six novel species within the genus Halorussus, for which the names Halorussus vallis sp. nov., Halorussus aquaticus sp. nov., Halorussus gelatinilyticus sp. nov., Halorussus limi sp. nov., Halorussus salilacus sp. nov., and Halorussus salinisoli sp. nov. are proposed.

Haladaptatus halobius sp. nov. and Haladaptatus salinisoli sp. nov., two extremely halophilic archaea isolated from Gobi saline soil

Two extremely halophilic archaeal strains, PSR5^T and PSR8^T, were isolated from a saline soil sample collected from the Tarim Basin, Xinjiang, PR China. Both strains had two copies of the 16S rRNA genes rrn1 and rrn2, showing 2.6 and 3.9% divergence, respectively. The rrn1 gene of PSR5^T showed 98.4 and 95.3% similarity to the rrn1 and rrn2 genes of strain PSR8^T; the rrn2 gene of PSR5^T displayed 97.4 and 96.7% similarity to those of strain PSR8^T, respectively. Phylogenetic analyses based on the 16S rRNA and rpoB' genes revealed that strains PSR5^T and PSR8^T formed a single cluster, and then tightly clustered with the current four Haladaptatus species (93.5-97.1% similarities for the 16S rRNA gene and 89.3-90.9% similarities for the rpoB' gene, respectively). Several phenotypic characteristics differentiate strains PSR5^T and PSR8^T from current Haladaptatus members. The polar lipids of the two strains are phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester phosphatidylglycerol sulphate and three glycolipids. One of the glycolipids is sulphated mannosyl glucosyl diether, and the remaining two glycolipids are unidentified. The average nucleotide identity, in silico DNA-DNA hybridization, amino acid identity and percentage of conserved proteins values between the two strains were 88.5, 39.1, 89.3 and 72.8 %, respectively, much lower than the threshold values proposed as a species boundary. These values among the two strains and Haladaptatus members were 77.9-79.2, 22.0-23.5, 75.1-78.2 and 56.8-69.9 %, respectively, much lower than the recommended threshold values for species delimitation. These results suggested that strains PSR5^T and PSR8^T represent two novel species of Haladaptatus. Based on phenotypic, chemotaxonomic, genomic and phylogenetic properties, strains PSR5^T (=CGMCC 1.16851^T=JCM 34141^T) and PSR8^T (=CGMCC 1.17025^T=JCM 34142^T) represent two novel species of the genus Haladaptatus, for which the names Haladaptatus halobius sp. nov. and Haladaptatus salinisoli sp. nov. are proposed.

Halorientalis salina sp. nov., Halorientalis marina sp. nov., Halorientalis litorea sp. nov.: three extremely halophilic archaea isolated from a salt lake and coarse sea salt

Three halophilic archaeal strains, NEN8^T, GDY88^T and ZY14^T, were isolated from a salt lake in Tibet and coarse sea salt samples from Guangdong and Hebei, China, respectively. These strains formed three separate clades (showing 94.4-95.8% and 87.1-89.4% similarities, respectively) and then clustered with the current Halorientalis members (showing 90.7-97.6% and 87.0-91.2% similarities, respectively), as revealed by phylogenetic analyses based on 16S rRNA and rpoB' genes. The overall genome-related index, average nucleotide identity (ANI), in silico DNA-DNA hybridization (DDH), average amino acid identity (AAI) and the percentage of conserved proteins (POCP) values, among the three strains and members of the genus Halorientalis were 76.0-88.0%, 21.3-37.2%, 69.0-88.3% and 57.7-78.1%, clearly below the threshold values for species demarcation. Strains NEN8^T, GDY88^T and ZY14^T could be distinguished from current Halorientalis species according to differential phenotypic characteristics. The major polar lipids of the three strains were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), sulfated mannosyl glucosyl diether (S-DGD-1) and disulfated mannosyl glucosyl diether (S₂-DGD). In addition, mannosyl glucosyl diether (DGD-1) was detected in strain NEN8^T and phosphatidic acid (PA), posssulfated galactosyl mannosyl glucosyl diether (S-TGD-1) and sulfated mannosyl glucosyl diether-phosphatidic acid (S-DGD-PA) were observed in strain ZY14^T. These results revealed that strains NEN8^T (= CGMCC 1.17213^T = JCM 34155^T), GDY88^T (= CGMCC 1.18548^T = JCM 34481^T) and ZY14^T (= CGMCC 1.17178^T = JCM 34154^T) represent three novel species of the genus Halorientalis, for which the names Halorientalis salina sp. nov., Halorientalis marina sp. nov. and Halorientalis litorea sp. nov. are proposed.

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.

Halorussus halobius sp. nov., Halorussus marinus sp. nov. and Halorussus pelagicus sp. nov., isolated from salted brown alga Laminaria

Four halophilic archaeal strains, designated HD8-83T, LYG-36T, DLLS-82 and RC-68T, were isolated from the salted brown alga Laminaria of three different origins (Dalian, Lianyungang, Dalian and Rongcheng) in PR China. All strains had pleomorphic rod cells that were motile, lysed in distilled water, stained Gram-negative, and formed red-pigmented colonies on agar plate (except for DLLS-82, which formed white colonies). Based on phylogenetic analyses of the 16S rRNA genes, strain HD8-83T was closely related to Halorussus litoreus HD8-51T (97.9 % similarity), strain LYG-36T and DLLS-82 to Halorussus rarus TBN4T (94.4 % and 94.7 % similarities, respectively), and strain RC-68T to Halorussus salinus YJ-37-HT (96.9 % similarity). Results of phylogenetic analyses based on rpoB' genes and 728 concatenated single-copy orthologous clusters also showed that these strains formed three different branches and clustered tightly with the Halorussus members. The average nucleotide identity, average amino acid identity and in silico DNA-DNA hybridization values between strains LYG-36T and DLLS-82 were 98.9, 98 and 92.4%, showing that they were different strains of the same species. While those values between the isolates and other Halorussus members were below 84.7, 82.9 and 28.9 %, respectively. Based on the phenotypic, chemotaxonomic and phylogenetic properties, strains HD8-83T, LYG-36T, DLLS-82 and RC-68T represent three novel species of the genus Halorussus for which the names Halorussus halobius sp. nov. (type strain: HD8-83T=CGMCC 1.15334T=JCM 31110T), Halorussus marinus sp. nov. (type strain: LYG-36T=CGMCC 1.13606T=JCM 32952T; reference strain: DLLS-82=CGMCC 1.13604=JCM 32951) and Halorussus pelagicus sp. nov. (type strain: RC-68T=CGMCC 1.13609T=JCM 32953T) are proposed.

Halobaculum rubrum sp. nov., an extremely halophilic archaeon isolated from a salt lake

A halophilic archaeal strain, designated C46T, was isolated from an inland salt lake in Qinghai Province, PR China. Results of phylogenetic analysis based on 16S rRNA gene sequences indicated that strain C46T belongs to the genus Halobaculum , and the closest phylogenetic relative is Halobaculum gomorrense DSM 9297T with 97.7 % similarity. Despite this, strain C46T was more related to Halobaculum saliterrae WSA2T than other members of the genus Halobaculum based on genome comparison and analysis, and the average nucleotide identity, in silico DNA–DNA hybridization, amino acid identity and percentage of conserved protein values between the two strains were 89.1, 53.3, 89.2 and 75.6 %, respectively, which are lower than the cutoff values proposed for species delimitation. The physiological, biochemical, genetic and genomic characteristics of strain C46T were different from those of its closest phylogenetic neighbours, which indicated that this strain represents a novel species of the genus Halobaculum , for which the name Halobaculum rubrum sp. nov. is proposed. The type strain is C46T (=CGMCC 1.13737T=JCM 32959T).

Diversity of the Tryptophanase Gene and Its Evolutionary Implications in Living Organisms

Tryptophanase encoded by the gene tnaA is a pyridoxal phosphate-dependent enzyme that catalyses the conversion of tryptophan to indole, which is commonly used as an intra- and interspecies signalling molecule, particularly by microbes. However, the production of indole is rare in eukaryotic organisms. A nucleotide and protein database search revealed tnaA is commonly reported in various Gram-negative bacteria, but that only a few Gram-positive bacteria and archaea possess the gene. The presence of tnaA in eukaryotes, particularly protozoans and marine organisms, demonstrates the importance of this gene in the animal kingdom. Here, we document the distribution of tnaA and its acquisition and expansion among different taxonomic groups, many of which are usually categorized as non-indole producers. This study provides an opportunity to understand the intriguing role played by tnaA, and its distribution among various types of organisms.

Halobaculum halophilum sp. nov. and Halobaculum salinum sp. nov., isolated from salt lake and saline soil

Two halophilic archaeal strains, Gai3-2^T and NJ-3-1^T, were isolated from salt lake and saline soil samples, respectively, collected in PR China. The 16S rRNA gene sequences of the two strains were 97.5% similar to each other. Strains Gai3-2^T and NJ-3-1^T had the highest sequence similarities to 'Halobonum tyrrellense' G22 (96.7 and 97.8%, respectively), and displayed similarities of 91.5-93.5% and 92.3-94.7%, respectively, to Halobaculum members. Phylogenetic analysis revealed that the two strains formed different branches and clustered tightly with 'H. tyrrellense' G22 and Halobaculum members. The average nucleotide identity (ANI), in silico DNA-DNA hybridization (isDDH) and amino acid identity (AAI) values between the two strains were 83.1, 26.9 and 77.9%, respectively, much lower than the threshold values proposed as a species boundary. These values between the two strains and 'H. tyrrellense' G22 (ANI 77.9-78.2%, isDDH 22.5-22.6% and AAI 68.8-69.3%) and Halobaculum members (ANI 77.53-77.63%, isDDH 21.8-22.3% and AAI 68.4-69.4%) were almost identical, and much lower than the recommended threshold values for species delimitation. These results suggested that strains Gai3-2^T and NJ-3-1^T represent two novel species of Halobaculum. Based on phenotypic, chemotaxonomic and phylogenetic properties, strains Gai3-2^T (=CGMCC 1.16080^T=JCM 33550^T) and NJ-3-1^T (=CGMCC 1.16040^T=JCM 33552^T) represent two novel species of the genus Halobaculum, for which the name Halobaculum halophilum sp. nov. and Halobaculum salinum sp. nov. are proposed.

Halosimplex halophilum sp. nov. and Halosimplex salinum sp. nov., isolated from saline soil and a salt mine

A polyphasic study was undertaken to determine the taxonomic position of two halophilic archaeal strains, TH32^T and YPL4^T, isolated from saline soil and a salt mine in PR China, respectively. Strains TH32^T and YPL4^T both have two dissimilar 16S rRNA genes. The two strains exhibited sequence similarities of 91.5-95.5 % for 16S rRNA genes and 90.9 % for the rpoB' gene. Sequence similarities of 16S rRNA genes and the rpoB' gene between the two strains and the current four members of Halosimplex were 90.6-97.4 % and 91.4-93.5 %, respectively. Phylogenetic analysis revealed that the two strains formed different branches separating them from the current Halosimplex members. Several phenotypic characteristics differentiate strains TH32^T and YPL4^T from current Halosimplex members. The polar lipids of the two strains are phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and four glycolipids. Two of the glycolipids are chromatographically identical to disulfated mannosyl glucosyl diether and sulfated mannosyl glucosyl diether, respectively, and the remaining two glycolipids are unidentified. The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (DDH) values between the two strains and the current members of Halosimplex (ANI 80.4-89.2 % and in silico DDH 24.0-41.8 %) were much lower than the threshold values proposed as a species boundary, suggesting that the two strains represent novel species of Halosimplex. The values between the two strains (ANI 81.3 % and in silico DDH 24.9 %) were also much lower than the recommended threshold values, which revealed that the two strains represent two genomically different species of Halosimplex. These results showed that strains TH32^T (=CGMCC 1.15190^T=JCM 30840^T) and YPL4^T (=CGMCC 1.15329^T=JCM 31108^T) represent two novel species of Halosimplex, for which the names Halosimplex halophilum sp. nov. and Halosimplex salinum sp. nov. are proposed.

Natronomonas halophila sp. nov. and Natronomonas salina sp. nov., two novel halophilic archaea

Two halophilic archaeal strains, C90^T and YPL13^T, were isolated from a salt lake and a salt mine in PR China. The two strains were found to form two clusters (97.5 and 89.5 % similarity between them, respectively) separating them from the three current members of the genus Natronomonas (95.4-97.0 % and 86.6-89.3 % similarity, respectively) on the basis of the 16S rRNA and rpoB' gene sequence similarities and phylogenetic analysis. Diverse phenotypic characteristics differentiate strains C90^T and YPL13^T from current Natronomonas members. The polar lipids of strain C90^T were phosphatidic acid, phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulphate, two unidentified glycolipids, a major glycolipid and a minor glycolipid, while those of strain YPL13^T were PG, PGP-Me, two unidentified phospholipids and a glycolipid. The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between the two strains were 79.8 and 27.1 %, respectively, which were much lower than the threshold values proposed as a species boundaries (ANI 95-96 % and isDDH 70 %), which revealed that the two strains represent two novel species; these values (ANI 76.6-80.0 % and isDDH 21.6-27.0 %) of the strains examined in this study and the current members of Natronomonas are much lower than the recommended threshold values, suggesting that strains C90^T and YPL13^T represent two genomically different species of Natronomonas. These results showed that strains C90^T (=CGMCC 1.13738^T=JCM 32961^T) and YPL13^T (=CGMCC 1.13884^T=JCM 31111^T) represent two novel species of Natronomonas, for which the names Natronomonas halophila sp. nov. and Natronomonas salina sp. nov. are proposed.