Halorubrum pallidum sp. nov., an extremely halophilic archaeon isolated from a subterranean rock salt

Abstract

An extremely halophilic archaeon, strain PJ61 T , was isolated from a subterranean rock salt of Yuanyongjing Salt Mine, Yunnan, China. Colonies were pale, smooth, convex, and round (1.0-2.0 mm in diameter) on nutrient agar plates. Cells of strain PJ61 T were spherical or oval , stained Gram-negative, and were non-motile. Optimal growth was observed with 3.4 M NaCl and at 38 C in aerobic conditions. Mg 2+ was required for growth. Phylogenetic analysis based on 16S rRNA gene sequence similarities showed that strain PJ61 T belonged to the genus Halorubrum and was closely related to Halorubrum laminariae R60 T (98.3 % 16S rRNA gene sequence similarity), Halorubrum salinum GX71 T (98.2 %) and other species of the genus Halorubrum (<98 %). Sequence similarities of rpoB¢ gene and ef-2 gene between strain PJ61 T and the species of the genus Halorubrum also showed that strain PJ61 T was closely related to strain Halorubrum salinum GX71 T (93.4 % for rpoB¢and 94.8 % for ef-2). The DNA-DNA relatedness between strains PJ61 T and Halorubrum laminariae R60 T was 33±0.5 %, while it was 37±0.4 % for Halorubrum salinum GX71 T . The DNA G+C content of strain PJ61 T was 65.1 mol%. The major polar lipids of strain PJ61 T consisted of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and sulfated mannosyl glucosyl diether. The phenotypic, chemotaxonomic and phylogenetic properties suggest that strain PJ61 T represents a novel species of the genus Halorubrum, for which the name Halorubrum pallidum sp. nov. is proposed. The type strain is PJ61 T (=CGMCC 1.15212 T =JCM 30955 T ).

Biochemical and Taxonomic Characterization of Novel Haloarchaeal Strains and Purification of the Recombinant Halotolerant α-Amylase Discovered in the Isolate

“…Isolates were plated on Halovibrio medium (without NaCl) (HiMedia) supplemented with different concentrations of NaCl (2, 5, 7, 10, 12, 15, 18, 20, 22, 25, 27 and 30%) to test salt tolerance. Growth at different pH (5.0, 6.5, 7.0, 8.0, 9.0, and 10.0) was examined using Halovibrio medium (without NaCl) supplemented with 25% NaCl as described earlier ( Chen et al, 2016 ). The pH was adjusted using different buffers: MES (pH 5.0–6.0), PIPES (pH 6.5–7.0), HEPES (pH 7.5–8.0), and CHES (pH 9.0–10).…”

Halomicrococcus hydrotolerans gen. nov., sp. nov., an extremely halophilic archaeon isolated from a subterranean salt deposit

“…Utilization of sole carbon and energy sources was tested in minimal medium containing (g l −1 ): NaCl, 200; yeast extract (Difco), 0.1; NH 4 Cl, 0.5; KH 2 PO 4 , 0.05; MgSO 4 ⋅7H 2 O, 20; KCl, 2; FeSO 4 ⋅7H 2 O, 0.036; and MnCl 2 ⋅4H 2 O, 0.00036 [10]. d -Glucose, d -mannose, d -galactose, d -fructose, l -sorbose, d -ribose, d -xylose, maltose, sucrose, lactose, starch, glycerol, mannitol, sorbitol, acetate, pyruvate, lactate, succinate, malate, fumarate, citrate, glycine, l -alanine, l -arginine, l -aspartate, l -glutamate, l -lysine and l -ornithine were used as sole carbon or/and energy sources with the final concentration at 10 g l −1 .…”

“…Cells of strain H22 T were alive after been kept in distilled water for 2 months. They were sensitive to (g per discunless indicated): rifampicin (5), bacitracin (0.04 IU) and novobiocin (30), but resistant to ampicillin (10), chloramphenicol (30), ciprofloxacin (5), erythromycin (15), kanamycin (10), neomycin (30), norfloxacin (10), penicillin G (10 IU), streptomycin (10), tetracycline (30) and vancomycin (30). Other phenotypic characteristics are shown in Table 1 and the species description.…”