Proposed minimal standards for description of new taxa of the class Halobacteria.

Halophilic archaea of the class Halobacteria are the most salt-requiring prokaryotes within the domain Archaea. In 1997, minimal standards for the description of new taxa in the order Halobacteriales were proposed. From then on, the taxonomy of the class Halobacteria provides an excellent example of how changing concepts on prokaryote taxonomy and the development of new methods were implemented. The last decades have witnessed a rapid expansion of the number of described taxa within the class Halobacteria coinciding with the era of genome sequencing development. The current members of the International Committee on Systematics of Prokaryotes Subcommittee on the Taxonomy of Halobacteria propose these revisions to the recommended minimal standards and encourage the use of advanced technologies in the taxonomic description of members of the Halobacteria. Most previously required and some recommended minimal standards for the description of new taxa in the class Halobacteria were retained in the present revision, but changes have been proposed in line with the new methodologies. In addition to the 16S rRNA gene, the rpoB' gene is an important molecular marker for the identification of members of the Halobacteria. Phylogenomic analysis based on concatenated conserved, single-copy marker genes is required to infer the taxonomic status of new taxa. The overall genome relatedness indexes have proven to be determinative in the classification of the taxa within the class Halobacteria. Average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values should be calculated for rigorous comparison among close relatives.

Halobacterium hubeiense sp. nov., a haloarchaeal species isolated from a bore core drilled in Hubei Province, PR China.

Eight colonies of live microbes were isolated from an extensively surface-sterilized halite sample which had been retrieved from a depth of 2000 m from a salt mine in the Qianjiang Depression, Hubei Province, PR China. The eight colonies, obtained after 4 weeks of incubation, were named JI20-1T-JI20-8 and JI20-1T was selected as the type strain. The strains have been previously described, including a genomic analysis based on the complete genome for strain JI20-1T and draft genomes for the other strains. In that study, the name Halobacterium hubeiense was suggested, based on the location of the drilling site. Previous phylogenomic analysis showed that strain JI20-1T is most closely related to the Permian isolate Halobacterium noricense from Alpine rock salt. The orthologous average nucleotide identity (orthoANI) and digital DNA-DNA hybridization (dDDH) percentages between the eight strains are 100-99.6 % and 99.8-96.4 %, respectively. The orthoANI and dDDH values of these strains with respect to the type strains of species of the genus Halobacterium are 89.9-78.2 % and 37.3-21.6 %, respectively, supporting their placement in a novel extremely halophilic archaeal species. The phylogenomic tree based on the comparison of sequences of 632 core-orthologous proteins confirmed the novel species status for these haloarchaea. The polar lipid profile includes phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate, and sulfated galactosyl mannosyl galactosyl glucosyl diether, a profile compatible with that of Halobacterium noricense. Based on genomic, phenotypic, and chemotaxonomic characterization, we propose strain JI20-1T (=DSM 114402T = HAMBI 3616T) as the type strain of a novel species in the genus Halobacterium, with the name Halobacterium hubeiense sp. nov.

Decoding the Genomic Profile of the Halomicroarcula Genus: Comparative Analysis and Characterization of Two Novel Species.

The genus Halomicroarcula, classified within the family Haloarculaceae, presently comprises eight haloarchaeal species isolated from diverse saline habitats, such as solar salterns, hypersaline soils, marine salt, and marine algae. Here, a detailed taxogenomic study and comparative genomic analysis of the genus Halomicroarcula was carried out. In addition, two strains, designated S1CR25-12T and S3CR25-11T, that were isolated from hypersaline soils located in the Odiel Saltmarshes in Huelva (Spain) were included in this study. The 16S rRNA and rpoB' gene sequence analyses affiliated the two strains to the genus Halomicroarcula. Typically, the species of the genus Halomicroarcula possess multiple heterogeneous copies of the 16S rRNA gene, which can lead to misclassification of the taxa and overestimation of the prokaryotic diversity. In contrast, the application of overall genome relatedness indexes (OGRIs) augments the capacity for the precise taxonomic classification and categorization of prokaryotic organisms. The relatedness indexes of the two new isolates, particularly digital DNA-DNA hybridization (dDDH), orthologous average nucleotide identity (OrthoANI), and average amino acid identity (AAI), confirmed that strains S1CR25-12T (= CECT 30620T = CCM 9252T) and S3CR25-11T (= CECT 30621T = CCM 9254T) constitute two novel species of the genus Halomicroarcula. The names Halomicroarcula saliterrae sp. nov. and Halomicroarcula onubensis sp. nov. are proposed for S1CR25-12T and S3CR25-11T, respectively. Metagenomic fragment recruitment analysis, conducted using seven shotgun metagenomic datasets, revealed that the species belonging to the genus Halomicroarcula were predominantly recruited from hypersaline soils found in the Odiel Saltmarshes and the ponds of salterns with high salt concentrations. This reinforces the understanding of the extreme halophilic characteristics associated with the genus Halomicroarcula. Finally, comparing pan-genomes across the twenty Halomicroarcula and Haloarcula species allowed for the identification of commonalities and differences between the species of these two related genera.

The Hypersaline Soils of the Odiel Saltmarshes Natural Area as a Source for Uncovering a New Taxon: Pseudidiomarina terrestris sp. nov.

The hypersaline soils of the Odiel Saltmarshes Natural Area are an extreme environment with high levels of some heavy metals; however, it is a relevant source of prokaryotic diversity that we aim to explore. In this study, six strains related to the halophilic genus Pseudidiomarina were isolated from this habitat. The phylogenetic study based on the 16S rRNA gene sequence and the fingerprinting analysis suggested that they constituted a single new species within the genus Pseudidiomarina. Comparative genomic analysis based on the OGRIs indices and the phylogeny inferred from the core genome were performed considering all the members of the family Idiomarinaceae. Additionally, a completed phenotypic characterization, as well as the fatty acid profile, were also carried out. Due to the characteristics of the habitat, genomic functions related to salinity and high heavy metal concentrations were studied, along with the global metabolism of the six isolates. Last, the ecological distribution of the isolates was studied in different hypersaline environments by genome recruitment. To sum up, the six strains constitute a new species within the genus Pseudidiomarina, for which the name Pseudidiomarina terrestris sp. nov. is proposed. The low abundance in all the studied hypersaline habitats indicates that it belongs to the rare biosphere in these habitats. In silico genome functional analysis suggests the presence of heavy metal transporters and pathways for nitrate reduction and nitrogen assimilation in low availability, among other metabolic traits.

A long-awaited taxogenomic investigation of the family Halomonadaceae.

The family Halomonadaceae is the largest family composed of halophilic bacteria, with more than 160 species with validly published names as of July 2023. Several classifications to circumscribe this family are available in major resources, such as those provided by the List of Prokaryotic names with Standing in Nomenclature (LPSN), NCBI Taxonomy, Genome Taxonomy Database (GTDB), and Bergey's Manual of Systematics of Archaea and Bacteria (BMSAB), with some degree of disagreement between them. Moreover, regardless of the classification adopted, the genus Halomonas is not phylogenetically consistent, likely because it has been used as a catch-all for newly described species within the family Halomonadaceae that could not be clearly accommodated in other Halomonadaceae genera. In the past decade, some taxonomic rearrangements have been conducted on the Halomonadaceae based on ribosomal and alternative single-copy housekeeping gene sequence analysis. High-throughput technologies have enabled access to the genome sequences of many type strains belonging to the family Halomonadaceae; however, genome-based studies specifically addressing its taxonomic status have not been performed to date. In this study, we accomplished the genome sequencing of 17 missing type strains of Halomonadaceae species that, together with other publicly available genome sequences, allowed us to re-evaluate the genetic relationship, phylogeny, and taxonomy of the species and genera within this family. The approach followed included the estimate of the Overall Genome Relatedness Indexes (OGRIs) such as the average amino acid identity (AAI), phylogenomic reconstructions using amino acid substitution matrices customized for the family Halomonadaceae, and the analysis of clade-specific signature genes. Based on our results, we conclude that the genus Halovibrio is obviously out of place within the family Halomonadaceae, and, on the other hand, we propose a division of the genus Halomonas into seven separate genera and the transfer of seven species from Halomonas to the genus Modicisalibacter, together with the emendation of the latter. Additionally, data from this study demonstrate the existence of various synonym species names in this family.

Helicobacter ibis sp. nov., isolated from faecal droppings of black-faced ibis (Theristicus melanopis).

As part of a larger study on Epsilonproteobacteria carried by wild birds in the city of Valdivia (southern Chile), two curved rod-shaped Gram-stain-negative strains (A82T and WB-40) were recovered from faecal samples and subjected to a taxonomic study. Results of a genus-specific PCR showed that these isolates belonged to the genus Helicobacter. Further identification by 16S rRNA and hsp60 (60 kDa heat-shock protein) gene sequence analysis revealed that they formed a separate phylogenetic clade, different from other known Helicobacter species with 'Helicobacter burdigaliensis' CNRCH 2005/566HT and Helicobacter valdiviensis WBE14T being the most closely related species. This was confirmed by core-genome phylogeny as well as digital DNA-DNA hybridization and average nucleotide identity analyses between the genomes of strains A82T and WB-40 and all other Helicobacter species. The draft genome sequences of A82T and WB-40, obtained by Illumina NextSeq 2000 sequencing, consisted of 1.6 Mb with a G+C content of 31.9-32.0 mol%. The results obtained from the phylogenetic and genomic characterization, together with their different morphological and biochemical features, revealed that these two strains represent a novel species, for which we propose the name Helicobacter ibis sp. nov. with A82T (=LMG 32718T=CCCT 22.04T) as the type strain.

Characterization of Haloarcula terrestris sp. nov. and reclassification of a Haloarcula species based on a taxogenomic approach.

An extremely halophilic archaeon, strain S1AR25-5AT, was isolated from a hypersaline soil sampled in Odiel Saltmarshes Natural Area (Huelva, Spain). The cells were Gram-stain-negative, motile, pleomorphic rods. Cell growth was observed in the presence of 15-30 % (w/v) NaCl [optimum, 25 % (w/v) NaCl], at pH 6.0-9.0 (optimum, pH 6.5-7.5) and at 25-50 °C (optimum, 37 °C). Based on the 16S rRNA and rpoB' gene sequence comparisons, strain S1AR25-5AT was affiliated to the genus Haloarcula. Taxogenomic analysis, including comparison of the genomes and the phylogenomic tree based on the core-orthologous proteins, together with the genomic indices, i.e., orthologous average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity, confirmed that strain S1AR25-5AT (=CCM 9249T=CECT 30619T) represents a new species of the genus Haloarcula, for which we propose the name Haloarcula terrestris sp. nov. The major polar lipids were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulphate and an unidentified glycolipid, which correlated with the lipid profile of species of the genus Haloarcula. In addition, based on the modern approach in description of species in taxonomy of prokaryotes, the above mentioned genomic indexes indicated that the species Haloarcula tradensis should be considered as a heterotypic synonym of Haloarcula argentinensis.

Biosynthetic gene profiling and genomic potential of the novel photosynthetic marine bacterium Roseibaca domitiana.

Shifting the bioprospecting targets toward underexplored bacterial groups combined with genome mining studies contributes to avoiding the rediscovery of known compounds by revealing novel, promising biosynthetic gene clusters (BGCs). With the aim of determining the biosynthetic potential of a novel marine bacterium, strain V10T, isolated from the Domitian littoral in Italy, a comparative phylogenomic mining study was performed across related photosynthetic bacterial groups from an evolutionary perspective. Studies on polyphasic and taxogenomics showed that this bacterium constitutes a new species, designated Roseibaca domitiana sp. nov. To date, this genus has only one other validly described species, which was isolated from a hypersaline Antarctic lake. The genomic evolutionary study linked to BGC diversity revealed that there is a close relationship between the phylogenetic distance of the members of the photosynthetic genera Roseibaca, Roseinatronobacter, and Rhodobaca and their BGC profiles, whose conservation pattern allows discriminating between these genera. On the contrary, the rest of the species related to Roseibaca domitiana exhibited an individual species pattern unrelated to genome size or source of isolation. This study showed that photosynthetic strains possess a streamlined content of BGCs, of which 94.34% of the clusters with biotechnological interest (NRPS, PKS, RRE, and RiPP) are completely new. Among these stand out T1PKS, exclusive of R. domitiana V10T, and RRE, highly conserved only in R. domitiana V10T and R. ekhonensis, both categories of BGCs involved in the synthesis of plant growth-promoting compounds and antitumoral compounds, respectively. In all cases, with very low homology with already patented molecules. Our findings reveal the high biosynthetic potential of infrequently cultured bacterial groups, suggesting the need to redirect attention to microbial minorities as a novel and vast source of bioactive compounds still to be exploited.

Natrinema salsiterrestre sp. nov., an extremely halophilic archaeon isolated from a hypersaline soil.

An extremely halophilic archaeal strain, designated S1CR25-10T, was isolated from hypersaline soil sampled in the Odiel Saltmarshes Natural Area in Southwestern Spain (Huelva) and subjected to a polyphasic taxonomic characterization. The cells were Gram-stain-negative, motile and their colonies were pink-pigmented. It was a strictly aerobic haloarchaeon that could grow at 25-55 °C (optimum, 37 °C), at pH 6.0-9.0 (optimum, pH 7.0-8.0) and in the presence of 12-30 % (w/v) total salts (optimum, 20-25 %, w/v). The phylogenetic analysis based on the comparison of the 16S rRNA gene sequences revealed that strain S1CR25-10T belongs to the genus Natrinema, with 98.9 % similarity to Natrinema salinisoli SLN56T. In addition, the values of orthologous average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity were below the threshold limits accepted for prokaryotic species delineation, with N. salinisoli SLN56T showing the highest relatedness values (92.6 % and 48.4 %, respectively). The major polar lipids were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and a glycolipid chromatographically identical to sulfated diglycosyl diether. The DNA G+C content of the isolate was 63.8 mol%. Based on the phylogenetic, phenotypic and chemotaxonomic characterization and the whole genome results, strain S1CR25-10T represents a new species within the genus Natrinema, for which the name Natrinema salsiterrestre sp. nov., with type strain S1CR25-10T (=CECT 30623T=CCM 9251T), is proposed.

A step into the rare biosphere: genomic features of the new genus Terrihalobacillus and the new species Aquibacillus salsiterrae from hypersaline soils.

Hypersaline soils are a source of prokaryotic diversity that has been overlooked until very recently. The phylum Bacillota, which includes the genus Aquibacillus, is one of the 26 phyla that inhabit the heavy metal contaminated soils of the Odiel Saltmarshers Natural Area (Southwest Spain), according to previous research. In this study, we isolated a total of 32 strains closely related to the genus Aquibacillus by the traditional dilution-plating technique. Phylogenetic studies clustered them into two groups, and comparative genomic analyses revealed that one of them represents a new species within the genus Aquibacillus, whereas the other cluster constitutes a novel genus of the family Bacillaceae. We propose the designations Aquibacillus salsiterrae sp. nov. and Terrihalobacillus insolitus gen. nov., sp. nov., respectively, for these two new taxa. Genome mining analysis revealed dissimilitude in the metabolic traits of the isolates and their closest related genera, remarkably the distinctive presence of the well-conserved pathway for the biosynthesis of molybdenum cofactor in the species of the genera Aquibacillus and Terrihalobacillus, along with genes that encode molybdoenzymes and molybdate transporters, scarcely found in metagenomic dataset from this area. In-silico studies of the osmoregulatory strategy revealed a salt-out mechanism in the new species, which harbor the genes for biosynthesis and transport of the compatible solutes ectoine and glycine betaine. Comparative genomics showed genes related to heavy metal resistance, which seem required due to the contamination in the sampling area. The low values in the genome recruitment analysis indicate that the new species of the two genera, Terrihalobacillus and Aquibacillus, belong to the rare biosphere of representative hypersaline environments.

Metagenomes of a Crystallizer Pond from Isla Cristina Saltern in Spain.

The metagenomic sequences of the prokaryotic microbiota from the brine of a crystallizer pond with 42% (wt/vol) salinity of a saltern located in Isla Cristina, Huelva, southwest Spain, were obtained by Illumina. Haloarchaea and members of the bacterial genus Salinibacter were the most abundant prokaryotes.

Genomic-based phylogenetic and metabolic analyses of the genus Natronomonas, and description of Natronomonas aquatica sp. nov.

The genus Natronomonas is classified on the family Haloarculaceae, within the class Halobacteria and currently includes six species isolated from salterns, saline or soda lakes, and salt mines. All are extremely halophilic (optimal growth at 20-25% [w/v] NaCl) and neutrophilic, except Natronomonas pharaonis, the type species of the genus, that is haloalkaliphilic (showing optimal growth at pH 9.0) and possesses distinct phenotypic features, such as a different polar lipid profile than the rest of species of the genus. We have carried out a genome-based study in order to determine the phylogenetic structure of the genus Natronomonas and elucidate its current taxonomic status. Overall genomic relatedness indexes, i.e., OrthoANI (Average Nucleotide Identity), dDDH (digital DNA-DNA hybridization), and AAI (Average Amino acid Identity), were determined with respect to the species of Natronomonas and other representative taxa of the class Halobacteria. Our data show that the six species of Natronomonas constitute a coherent cluster at the genus level. Besides, we have characterized a new haloarchaeon, strain F2-12T, isolated from the brine of a pond of a saltern in Isla Cristina, Huelva, Spain, and we determined that it constitutes a new species of Natronomonas, for which we propose the name Natronomonas aquatica sp. nov. Besides, the metabolic analysis revealed a heterotrophic lifestyle and a versatile nitrogen metabolism for members of this genus. Finally, metagenomic fragment recruitments from a subset of hypersaline habitats, indicated that the species of Natronomonas are widely distributed in saline lakes and salterns as well as on saline soils. Species of this haloarchaeal genus can be considered as ubiquitous in intermediate to high salinity habitats.

Biotin pathway in novel Fodinibius salsisoli sp. nov., isolated from hypersaline soils and reclassification of the genus Aliifodinibius as Fodinibius.

Hypersaline soils are extreme environments that have received little attention until the last few years. Their halophilic prokaryotic population seems to be more diverse than those of well-known aquatic systems. Among those inhabitants, representatives of the family Balneolaceae (phylum Balneolota) have been described to be abundant, but very few members have been isolated and characterized to date. This family comprises the genera Aliifodinibius and Fodinibius along with four others. A novel strain, designated 1BSP15-2V2T, has been isolated from hypersaline soils located in the Odiel Saltmarshes Natural Area (Southwest Spain), which appears to represent a new species related to the genus Aliifodinibius. However, comparative genomic analyses of members of the family Balneolaceae have revealed that the genera Aliifodinibius and Fodinibius belong to a single genus, hence we propose the reclassification of the species of the genus Aliifodinibius into the genus Fodinibius, which was first described. The novel strain is thus described as Fodinibius salsisoli sp. nov., with 1BSP15-2V2T (=CCM 9117T = CECT 30246T) as the designated type strain. This species and other closely related ones show abundant genomic recruitment within 80-90% identity range when searched against several hypersaline soil metagenomic databases investigated. This might suggest that there are still uncultured, yet abundant closely related representatives to this family present in these environments. In-depth in-silico analysis of the metabolism of Fodinibius showed that the biotin biosynthesis pathway was present in the genomes of strain 1BSP15-2V2T and other species of the family Balneolaceae, which could entail major implications in their community role providing this vitamin to other organisms that depend on an exogenous source of this nutrient.

Genomic study and lipidomic bioassay of Leeuwenhoekiella parthenopeia: A novel rare biosphere marine bacterium that inhibits tumor cell viability.

The fraction of low-abundance microbiota in the marine environment is a promising target for discovering new bioactive molecules with pharmaceutical applications. Phenomena in the ocean such as diel vertical migration (DVM) and seasonal dynamic events influence the pattern of diversity of marine bacteria, conditioning the probability of isolation of uncultured bacteria. In this study, we report a new marine bacterium belonging to the rare biosphere, Leeuwenhoekiella parthenopeia sp. nov. Mr9T, which was isolated employing seasonal and diel sampling approaches. Its complete characterization, ecology, biosynthetic gene profiling of the whole genus Leeuwenhoekiella, and bioactivity of its extract on human cells are reported. The phylogenomic and microbial diversity studies demonstrated that this bacterium is a new and rare species, barely representing 0.0029% of the bacterial community in Mediterranean Sea metagenomes. The biosynthetic profiling of species of the genus Leeuwenhoekiella showed nine functionally related gene cluster families (GCF), none were associated with pathways responsible to produce known compounds or registered patents, therefore revealing its potential to synthesize novel bioactive compounds. In vitro screenings of L. parthenopeia Mr9T showed that the total lipid content (lipidome) of the cell membrane reduces the prostatic and brain tumor cell viability with a lower effect on normal cells. The lipidome consisted of sulfobacin A, WB 3559A, WB 3559B, docosenamide, topostin B-567, and unknown compounds. Therefore, the bioactivity could be attributed to any of these individual compounds or due to their synergistic effect. Beyond the rarity and biosynthetic potential of this bacterium, the importance and novelty of this study is the employment of sampling strategies based on ecological factors to reach the hidden microbiota, as well as the use of bacterial membrane constituents as potential novel therapeutics. Our findings open new perspectives on cultivation and the relationship between bacterial biological membrane components and their bioactivity in eukaryotic cells, encouraging similar studies in other members of the rare biosphere.

Phylogenomics of Haloarchaea: The Controversy of the Genera Natrinema-Haloterrigena.

The haloarchaeal genera Natrinema and Haloterrigena were described almost simultaneously by two different research groups and some strains studied separately were described as different species of these genera. Furthermore, the description of additional species were assigned to either Natrinema or Haloterrigena, mainly on the basis of the phylogenetic comparative analysis of single genes (16S rRNA gene and more recently rpoB' gene), but these species were not adequately separated or assigned to the corresponding genus. Some studies suggested that the species of these two genera should be unified into a single genus, while other studies indicated that the genera should remain but some of the species should be reassigned. In this study, we have sequenced or collected the genomes of the type strains of species of Natrinema and Haloterrigena and we have carried out a comparative genomic analysis in order to clarify the controversy related to these two genera. The phylogenomic analysis based on the comparison of 525 translated single-copy orthologous genes and the Overall Genome Relatedness Indexes (i.e., AAI, POCP, ANI, and dDDH) clearly indicate that the species Haloterrigena hispanica, Haloterrigena limicola, Haloterrigena longa, Haloterrigena mahii, Haloterrigena saccharevitans, Haloterrigena thermotolerans, and Halopiger salifodinae should be transferred to the genus Natrinema, as Natrinema hispanicum, Natrinema limicola, Natrinema longum, Natrinema mahii, Natrinema saccharevitans, Natrinema thermotolerans, and Natrinema salifodinae, respectively. On the contrary, the species Haloterrigena turkmenica, Haloterrigena salifodinae, and Haloterrigena salina will remain as the only representative species of the genus Haloterrigena. Besides, the species Haloterrigena daqingensis should be reclassified as a member of the genus Natronorubrum, as Natronorubrum daqingense. At the species level, Haloterrigena jeotgali and Natrinema ejinorense should be considered as a later heterotypic synonyms of the species Haloterrigena (Natrinema) thermotolerans and Haloterrigena (Natrinema) longa, respectively. Synteny analysis and phenotypic features also supported those proposals.

Taxogenomic and Comparative Genomic Analysis of the Genus Saccharomonospora Focused on the Identification of Biosynthetic Clusters PKS and NRPS.

Actinobacteria are prokaryotes with a large biotechnological interest due to their ability to produce secondary metabolites, produced by two main biosynthetic gene clusters (BGCs): polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS). Most studies on bioactive products have been carried out on actinobacteria isolated from soil, freshwater or marine habitats, while very few have been focused on halophilic actinobacteria isolated from extreme environments. In this study we have carried out a comparative genomic analysis of the actinobacterial genus Saccharomonospora, which includes species isolated from soils, lake sediments, marine or hypersaline habitats. A total of 19 genome sequences of members of Saccharomonospora were retrieved and analyzed. We compared the 16S rRNA gene-based phylogeny of this genus with evolutionary relationships inferred using a phylogenomic approach obtaining almost identical topologies between both strategies. This method allowed us to unequivocally assign strains into species and to identify some taxonomic relationships that need to be revised. Our study supports a recent speciation event occurring between Saccharomonospora halophila and Saccharomonospora iraqiensis. Concerning the identification of BGCs, a total of 18 different types of BGCs were detected in the analyzed genomes of Saccharomonospora, including PKS, NRPS and hybrid clusters which might be able to synthetize 40 different putative products. In comparison to other genera of the Actinobacteria, members of the genus Saccharomonospora showed a high degree of novelty and diversity of BGCs.

Draft Genome Sequence of Saccharomonospora piscinae KCTC 19743T, an Actinobacterium Containing Secondary Metabolite Biosynthetic Gene Clusters.

The draft genome sequence of Saccharomonospora piscinae KCTC 19743T, with a size of 4,897,614 bp, was assembled into 11 scaffolds containing 4,561 open reading frames and a G+C content of 71.0 mol%. Polyketide synthase and nonribosomal peptide synthetase gene clusters, which are responsible for the biosynthesis of several biomolecules, were identified and located in different regions in the genome.

Genome-based analyses reveal a synonymy among Halorubrum distributum Zvyagintseva and Tarasov 1989; Oren and Ventosa 1996, Halorubrum terrestre Ventosa et al. 2004, Halorubrum arcis Xu et al. 2007 and Halorubrum litoreum Cui et al. 2007. Emended description of Halorubrum distributum Zvyagintseva and Tarasov 1989; Oren and Ventosa 1996.

A comparative taxonomic study of Halorubrum distributum, Halorubrum terrestre, Halorubrum arcis and Halorubrum litoreum was carried out using different approaches, 16S rRNA gene sequence analysis, multilocus sequence analysis (MLSA), phylogenomic analysis based on the comparison of the core genome, orthologous average nucleotide identity (OrthoANI), Genome-to-Genome Distance Calculator (GGDC), synteny plots and polar lipid profile (PLP). The MLSA study, using the five concatenated housekeeping genes atpB, EF-2, glnA, ppsA and rpoB', and the phylogenomic analysis based on 1347 core translated gene sequences obtained from their genomes showed that Halorubrum distributum JCM 9100T, Halorubrum terrestre JCM 10247T, Halorubrum arcis JCM 13916T and Halorubrum litoreum JCM 13561T formed a robust cluster, clearly separated from the rest of species of the genus Halorubrum. The OrthoANI and digital DDH values, calculated by the GGDC, showed percentages among Hrr. distributum JCM 9100T, Hrr. terrestre JCM 10247T, Hrr. arcis JCM 13916T and Hrr. litoreum JCM 13561T that ranged from 98.1 to 97.5 %, and 84.0 to 78.0 %, respectively, while these values among those strains and the type strains of their most related species of Halorubrum were equal or lower than 90.8 and 41.2 %, respectively. Moreover, degree of synteny across the four genomes was very high, especially between the genomes of Halorubrum litoreum JCM 13561T and Halorubrum arcis JCM 13916T. In addition, the PLP is quite similar among the four strains studied, showing a common pattern typical of the neutrophilic species of the genus Halorubrum. Overall, these data show that Hrr. distributum, Hrr. terrestre, Hrr. arcis and Hrr. litoreum constitute a single species. Thus, the latter three should be considered as later, heterotypic synonyms of Hrr. distributum based on the rules for priority of names. We propose an emended description of Hrr. distributum, including the features of Hrr. terrestre, Hrr. arcis and Hrr. litoreum.