Halobellus captivus sp. nov., an extremely halophilic archaeon isolated from a subterranean salt mine

Genome-based classification of Halobellus rubicundus sp. nov., a novel extremely halophilic archaeon isolated from a Korean solar saltern

A novel extremely halophilic archaeon designated, MBLA0158T, was isolated from a solar saltern in Sorae, Republic of Korea. The colonies are red-pigmented, Gram-stain-negative, pleomorphic, non-motile, and lysed in distilled water. The strain grows at 25-45 °C (optimum, 37 °C), in 15-30% (w/v) NaCl (optimum, 20%) and 0.1-1.0 M Mg2+ (optimum, 0.2-0.3 M) at pH 6.0-10.0 (optimum, 7.0-8.0). Comparative analysis based on the 16S rRNA gene sequence revealed that this strain is most closely related to the Halobellus inordinatus YC20T with a sequence identity of 96.0%. Strain MBLA0158T contained phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester as major polar lipids. The genome size is 3.29 Mb and the DNA G + C content is 66.9 mol%. Phylogenomic analysis confirmed that strain MBLA0158T is distinct from previously reported type strains of the genus Halobellus. Pan-genome analysis showed that strain MBLA0158T contains 419 genes that are not present in other type strains of the genus Halobellus. Based on overall analyses, strain MBLA0158T is considered to represent a new species of the genus Halobellus, for which the name Halobellus rubicundus sp. nov. is proposed. The type strain is MBLA0158T (= KCTC 4318T = JCM 36642T).

A first insight into the Polish Bochnia Salt Mine metagenome

The Bochnia Salt Mine is one of the oldest mines in Europe. It was established in the thirteenth century, and actively operated until 1990. The mine has been placed on the UNESCO World Heritage List. Previous research describing Polish salt mines has been focused on bioaerosol characteristics and the identification of microorganisms potentially important for human health. The use of Polish salt mines as inhalation chambers for patients of health resorts has also been investigated. Nevertheless, the biodiversity of salt mines associated with biotechnological potential has not been well characterized. The present study paper examines the biodiversity of microorganisms in the Bochnia Salt Mine based on 16S rRNA gene and shotgun sequencing. Biodiversity studies revealed a significantly higher relative abundance of Chlamydiae at the first level of the mine (3.5%) compared to the other levels (< 0.1%). Patescibacteria microorganisms constituted a high percentage (21.6%) in the sample from site RA6. Shotgun sequencing identified 16 unique metagenome-assembled genomes (MAGs). Although one was identified as Halobacterium bonnevillei, the others have not yet been assigned to any species; it is possible that these species may be undescribed. Preliminary analyses of the biotechnological and pharmaceutical potential of microorganisms inhabiting the mine were also performed, and the biosynthetic gene cluster (BGC) profiles and antimicrobial peptide (AMP) coding genes in individual samples were characterized. Hundreds of BGCs and dozens of AMP coding genes were identified in metagenomes. Our findings indicate that Polish salt mines are promising sites for further research aimed at identifying microorganisms that are producers of potentially important substances with biotechnological and pharmaceutical applications.

Halobellus ruber sp. nov., a deep red-pigmented extremely halophilic archaeon isolated from a Korean solar saltern

A novel halophilic archaeon, strain MBLA0160^T, was isolated from a solar saltern in Sorae, Republic of Korea. The cells are deep-red pigmented, Gram-negative, rod shaped, motile, and lysed in distilled water. The strain MBLA0160^T grew at 25-45 °C (optimum 37 °C), in 15-30% (w/v) NaCl (optimum 20%) and 0.1-1.0 M MgCl₂ (optimum 0.3-0.5 M) at pH 5.0-9.0 (optimum 7.0). Phylogenetic analysis based on the 16S rRNA sequence showed that this strain was related to two species within the genus Halobellus (Hbs.), with 98.4% and 95.8% similarity to Hbs. salinus CSW2.24.4 ^T and Hbs. clavatus TNN18^T, respectively. The major polar lipids of the strain MBLA160^T were phosphatidylglycerol, phosphatidylglycerol sulfate, and phosphatidylglycerol phosphate methyl ester. The genome size, G + C content, and N50 value of MBLA0160^T were 3.49 Mb, 66.5 mol%, and 620,127 bp, respectively. According to predicted functional proteins of strain MBLA0160^T, the highest category was amino acid transport and metabolism. Genome rapid annotation showed that amino acid and derivatives was the most subsystem feature counts. Pan-genomic analysis showed that strain MBLA0160^T had 97 annotated unique KEGG, which were mainly included metabolism and environmental information processing. Ortholog average nucleotide identities (OrthoANI) and in silico DNA-DNA hybridization (isDDH) values between the strain MBLA0160^T and other strains of the genus Halobellus were under 84,4% and 28.1%, respectively. The genome of strain MBLA0160^T also contain the biosynthetic gene cluster for C₅₀ carotenoid as secondary metabolite. Based on the phylogenetic, phenotypic, chemotaxonomic properties, and comparative genomic analyses, strain MBLA0160^T is considered to represent a novel species of the genus Halobellus, for which the name Halobellus ruber sp. nov. is proposed. The type strain is MBLA0160^T (= KCTC 4291 ^T = JCM 34172 ^T).