Halocalculus aciditolerans gen. nov., sp. nov., an acid-tolerant haloarchaeon isolated from commercial salt

Abstract

Three halophilic archaeal strains, MH2-243-1 T , MH2-93-1 and MH2-91-1 were isolated from commercial salt samples from Japan, Australia, and Bolivia. Strain MH2-243-1 T was able to grow in the presence of 12-30 % (w/v) NaCl (optimum, 18 % NaCl), at pH 4.5-7.0 (optimum, pH 6.0) and at 20-60 6C (optimum, 40 6C). Strains MH2-91-1 and MH2-93-1 grew in slightly different ranges. The orthologous 16S rRNA gene sequences of the three strains were almost identical (99.8-99.9 % similarities), and the closest relative was Salarchaeum japonicum JCM 16327 T with 94.2-94.3 % 16S rRNA gene sequence similarities, followed by strains of members of the closely related genera Halobacterium and Halarchaeum. The RNA polymerase subunit B9 gene (rpoB9) sequence also showed the highest similarity (86.6 %) to that of Salarchaeum japonicum JCM 16327 T. The DNA G+C contents of strains MH2-243-1 T , MH2-93-1 and MH2-91-1 were 68.5, 68.8 and 68.3 mol%, respectively. DNA-DNA relatedness values amongst the three strains were 97-99 %. The polar lipids of the three strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, and at least seven unidentified glycolipids. The polar lipid composition differed from those of Salarchaeum japonicum and species of the genera Halobacterium and Halarchaeum. Based on the phenotypic and phylogenetic analyses, it is proposed that the isolates represent a novel species of a new genus, for which the name Halocalculus aciditolerans gen. nov., sp. nov. is proposed. The type strain of the type species is MH2-243-1 T (5JCM 19596 T 5KCTC 4149 T) isolated from solar salt produced in Japan. MH2-93-1 (5JCM 19595) and MH2-91-1 (5JCM 19594) are additional strains of the type species. Many haloarchaeal strains grow well in neutral to slightly alkaline media, and alkaliphilic haloarchaea have been isolated from various sources (Oren, 2012). In 2008, we showed the presence of moderately acidophilic haloarchaeal strains capable of growth in the medium MH1 adjusted to pH 4.5. They were isolated from many solar salt samples obtained from Australia, Indonesia, Japan, Mexico, the Philippines, etc. (Minegishi et al., 2008). Most strains grew at a pH range of 4.5-6.0, and none of them showed growth at pH higher than 6.5. A representative Abbreviations: ML, maximum-likelihood; NJ, neighbour-joining; PGP-Me, phosphatidylglycerol phosphate methyl ester. The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequence of strains MH2-243-1 T , MH2-93-1 and MH2-91-1 are AB844670, AB844667 and AB844666, respectively; those for the rpoB9 sequence of the same strains are AB917096, AB917095 and AB917094, respectively. Two supplementary figures are available with the online Supplementary Material.

Halorussus amylolyticus sp. nov., isolated from an inland salt lake

“…At the time of writing, the class Halobacteria contains a single order, Halobacteriales , containing a single family, Halobacteriaceae (Oren, 2014). The family Halobacteriaceae encompasses 50 genera containing over 195 species (Oren, 2012, 2014; Han et al , 2014; Liu et al , 2014, 2015; Song et al , 2014; Zhang & Cui, 2014; Amoozegar et al , 2015; Corral et al , 2015; Minegishi et al , 2015). During our survey on halophilic archaeal diversity of an inland salt lake of China (Zhang et al , 2013), we obtained a halophilic archaeal strain, YC93 T , which was most closely related to members of the genus Halorussus , as judged based on 16S rRNA gene sequences.…”

Genome-based classification of the class Halobacteria and description of Haladaptataceae fam. nov. and Halorubellaceae fam. nov

“…Putting aside these three problematic species, the current 76 genera with validly published names gathered into eight, tightly clustered, monophyletic groups which were supported by high bootstrap values and separated from the ‘ Halorutilaceae ’ of the ‘ Halorutilales ’ recently described by Durán-Viseras et al [8]. The species of the genera Halanaeroarchaeum [21], Halarchaeum [22], Halobacterium [23], Halocalculus [24], Halodesulfurarchaeum [25] and Salarchaeum [26] formed the Halobacteriaceae , this assignment is consistent with that of GTDB but different from that proposed by Gupta et al [5, 6]. The family ‘ Haladaptataceae ’ has been proposed previously, only including the single genus Haladaptatus [9, 27] and the family name has not been validly published to date.…”

Halospeciosus flavus gen. nov., sp. nov. and Haladaptatus caseinilyticus sp. nov., halophilic archaea isolated from saline soil of an inland solar saltern and offshore sediment

“…Strain XZGYJ-43 T was able to grow with 0.9-4.8 M NaCl (optimum, 2.0 M), with 0-1.0 M MgCl 2 (optimum, 0.5 M), at pH 5.5-8.5 (optimum, pH 7.0) and at 20-42 °C (optimum, 30 °C). Some strains of the family Halobacteriaceae can use different electron acceptors, such as nitrate, dimethyl sulphoxide and fumarate, while a few of them can utilize arginine [35][36][37]. Strain XZGYJ-43 T could grow anaerobically in the presence of nitrate and DMSO, but not with arginine.…”