Halorubrum aethiopicum sp. nov., an extremely halophilic archaeon isolated from commercial rock salt.

A novel extremely halophilic archaeon, designated SAH-A6T, was isolated from a sample of commercial rock salt in Ethiopia. Cells of SAH-A6T were aerobic and pleomorphic. The strain was able to grow at concentrations of 15-30 % (w/v) NaCl (optimum 20-25 % NaCl), at pH 6.0-9.0 (optimum pH 7.0) and in a temperature range of 30-55 °C (optimum 37-45 °C). Mg2+ was not required for growth of SAH-A6T cells. On the basis of 16S rRNA gene sequence analysis, strain SAH-A6T was closely related to Halorubrum halodurans Cb34T (99.1 %), Halorubrum rubrum YC87T (98.9 %), Halorubrum aquaticum EN-2T (98.7 %), Halorubrum cibi JCM 15757T (98.4 %), Halorubrum luteum CGSA15T (97.3 %), Halorubrum lipolyticum 9-3T (97.1 %), Halorubrum tibetense 8W8T (97.1 %), Halorubrum kocurii JCM 1478T (97.1 %), Halorubrum halophilum B8T (97.0 %) and Halorubrum persicum C49T (97.0 %). Phylogenetic analysis based on the rpoB' gene sequences showed that strain SAH-A6T was closely related to Hrr. halodurans Cb34T (99.7 %), Hrr. aquaticum JCM 14031T (99.3 %) and other members of the genus Halorubrum (<99.0 %). The DNA G+C content of the strain was 68.0 mol%. DNA-DNA hybridization between strain SAH-A6T and the most closely related members of the genus Halorubrum were below 55 %, suggesting that the new isolate constitutes a different genospecies. On the bases of chemotaxonomic, phenotypic and genotypic data, strain SAH-A6T (=KCCM 43215T=JCM 31519T) represents a novel species of the genus Halorubrum, for which the name Halorubrumaethiopicum sp. nov. is proposed.

Diversity of Extremely Halophilic Archaeal and Bacterial Communities from Commercial Salts.

Salting is one of the oldest food preservation techniques. However, salt is also the source of living halophilic microorganisms that may affect human health. In order to determine the microbial communities of commercial salts, an investigation were done using amplicon sequencing approach in four commercial salts: Ethiopian Afdera salt (EAS), Ethiopian rock salt (ERS), Korean Jangpan salt (KJS), and Korean Topan salt (KTS). Using domain-specific primers, a region of the 16S rRNA gene was amplified and sequenced using a Roche 454 instrument. The results indicated that these microbial communities contained 48.22-61.4% Bacteria, 37.72-51.26% Archaea, 0.51-0.86% Eukarya, and 0.005-0.009% unclassified reads. Among bacteria, the communities in these salts were dominated by the phyla Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. Of the archaea, 91.58% belonged to the class Halobacteria, whereas the remaining 7.58, 0.83, and 0.01% were Nanoarchaea, Methanobacteria, and Thermococci, respectively. This comparison of microbial diversity in salts from two countries showed the presence of many archaeal and bacterial genera that occurred in salt samples from one country but not the other. The bacterial genera Enterobacter and Halovibrio were found only in Korean and Ethiopian salts, respectively. This study indicated the occurrence and diversity of halophilic bacteria and archaea in commercial salts that could be important in the gastrointestinal tract after ingestion.

Draft genome sequence of the extremely halophilic Halorubrum sp. SAH-A6 isolated from rock salts of the Danakil depression, Ethiopia.

The draft genome sequence of Halorubrum sp. SAH-A6, isolated from commercial rock salts of the Danakil depression, Ethiopia. The genome comprised 3,325,770 bp, with the G + C content of 68.0%. The strain has many genes which are responsible for secondary metabolites biosynthesis, transport and catabolism as compared to other Halorubrum archaea members. Abundant genes responsible for numerous transport systems, solute accumulation, and aromatic/sulfur decomposition were detected. The first genomic analysis encourages further research on comparative genomics, and biotechnological applications. The NCBI accession number for this genome is SAMN04278861 and ID: 4278861 and strain deposited with accession number KCTC 43215.