TL;DR
On the basis of the combined phenotypic, chemotaxonomic, phylogenetic and genomic evidence, strain GXG 6511T is considered to represent a novel species of the genus Ammonicoccus, for which the name Ammonicoccus luteus sp.
Abstract A novel psychrophilic member of the phylum Actinomycetota, designated strain CPHL_1T, was isolated from the shoreline of Cape Hallett, Antarctica. Cells were Gram-positive, aerobic, non-motile, non-spore-forming rods (0.7–1.0 µm in length) with orange to yellow pigmentation. Optimal growth occurred at 15 °C, pH 8.0, with NaCl tolerance up to 3% (w/v). Strain CPHL_1T exhibited cytosolic cold-active β-galactosidase activity, with an optimum at 15 °C and pH 7.0 and formed non-adherent biofilms. Phylogenetic analysis based on 16S rRNA gene sequence placed the strain within the genus Rhodoglobus, showing high similarity to Rhodoglobus vestalii LV3T (99.4%) and Rhodoglobus aureus CMS 81yT (97.6%). Chemotaxonomic characteristics, including the predominance of anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0 fatty acids, the presence of MK-11, MK-10 and MK-12 as the major respiratory quinones, and genomic G+C content of 60%, further supported its assignment to the genus Rhodoglobus. Whole-genome comparisons revealed clear taxonomic distinction, with strain CPHL_1T sharing 88.9% average nucleotide identity (ANI) and 38.3% digital DNA–DNA hybridization (dDDH) values with R. aureus, and 81.7% ANI and 25.1% dDDH with R. vestalii, confirming its status as a novel species. Phylogenetic analysis revealed that the β-galactosidases from these Rhodoglobus strains form a well-supported clade with high sequence similarity. Based on these data, a novel species is proposed: Rhodoglobus galactosidasius sp. nov. (type strain CPHL_1T =ITEM 19986T =KCTC 59592T). Genomic analyses also highlighted its biosynthetic potential for specialized metabolites, consistent with the recognized metabolic diversity of the genus.
Comparative genomic analysis andylogenetic analysis revealed that the strain H202T belonged to the genus Actinopolyspora and showed the highest sequence similarity to Actinopolyspora mzabensis DSM 45460T, suggesting that this strain represents a novel species.
Novel facultatively anaerobic moderately thermophilic bacteria, strains OK-6-MeT and OK-1-Me, were isolated from the hot springs of Karmadon (North Ossetia, Russian Federation). Gram-stain-negative, motile rods were present singly, in rosettes, and formed biofilms. Both strains grew optimally at 55 °C, pH 7.0 and did not require sodium chloride. They were chemoorganoheterotrophs, growing on mono-, di- and polysaccharides (cellulose, xylan, lichenan, xyloglucan, mannan, locust bean gum, pectin) as well as proteinaceous substrates (gelatin, casein). Growth under anaerobic conditions was observed both in the presence and absence of external electron acceptors (sulfur, thiosulfate, nitrite, arsenate, Fe-citrate, ferrihydrite). Major cellular fatty acids of both strains were iso-C15:0, anteiso-C15:0, and anteiso-C17:0. The size of the genomes were 3.3 and 3.2 Mb for strain OK-6-MeT and OK-1-Me, respectively. Genomic DNA G + C content was 37% for both strains. According to the 16S rRNA gene sequence and conserved protein sequences phylogenies, the strains represented a new species of the genus Melioribacter of family Melioribacteraceae within the class Ignavibacteria, for which the name Melioribacter sulfuriphilus sp. nov. is proposed, with type strain OK-6-MeT (= B-3972T = CGMCC 1.18264 T = BIM B-2154T = UQM 41932T). Analysis of OK-1 and OK-6 metagenomes revealed presence of various genes involved in carbon (CO2 fixation, carbohydrate hydrolysis, hydrocarbons degradation, fermentation), nitrogen (nitrate, nitrite, NO and N2O reduction) and sulfur cycles (sulfate reduction, sulfur or thiosulfate reduction, oxidation of sulfur compounds). MAGs OK-1-035 and OK-6-024 almost identical to genomes of strain OK-1-Me and OK-6-MeT presumably are integral part of these complex trophic chains.
Based on further phenotypic, genomic, and phylogenetic analysis, strain F2T represents a novel genus and species within the family Anaerovoracaceae with the proposed name Peptonella octanoica gen. sp.
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