Actinopolyspora sabaoui sp. nov., a novel halophilic actinobacterium isolated from Ghardaïa soil, Algeria.

Actinomycetospora lichenicola sp. nov., a rare actinomycete isolated from the crustose lichen Arthonia leioplacella.

Polyphasic and genomic characterisation of Streptomyces zimensis sp. nov., a halotolerant Actinomycetota from the Saline Lake Zima in Morocco

Members of the phylum Actinomycetota are widely distributed across diverse environments and are well known for their metabolic versatility and capacity to produce bioactive compounds. In this study, strain ZE1316R2Aᵀ was isolated from the saline water collected from Lake Zima (Morocco) and subjected to comprehensive polyphasic taxonomic characterisation. Phylogenetic analysis based on the 16 S rRNA gene placed strain ZE1316R2Aᵀ within the genus Streptomyces , showing highest sequence similarity with S. albidoflavus DSM 40,455 T (99.71%). However, genome-based indices, including average nucleotide identity (ANIb = 94.84%, ANIm = 96.09%) and digital DNA-DNA hybridization (dDDH = 64.9%), supported its distinction as a separate species. The draft genome (7.41 Mb; G + C = 73.26 mol%) comprises 6,464 coding sequences and reveals the presence of strain-specific genomic regions and biosynthetic gene clusters. Comparative analyses highlighted both a conserved core genome and a substantial accessory genome component, reflecting genomic differentiation relative to closely related taxa. Phenotypic and chemotaxonomic characteristics were consistent with assignment to the genus Streptomyces , while supporting its differentiation at the species level. Based on the combined genomic, phenotypic, and chemotaxonomic evidence, strain ZE1316R2Aᵀ represents a novel species of the genus Streptomyces , for which the name Streptomyces zimensis sp. nov., is proposed. This study expands current knowledge of Streptomyces diversity associated with saline environments and highlights the genomic diversity present within closely related taxa. The type strain is ZE1316R2Aᵀ (= CCMM B1331 T  = DSM 120541 T ).

Ammonicoccus luteus sp. nov., a novel actinobacterium isolated from the intestine of Argyrosomus argentatus

Altererythrobacter chaiwopuensis sp. nov., a novel alphaproteobacterial strain isolated from sediment of the Chaiwopu Lake

Abstract Two alphaproteobacterial strains, designated EGI L300112T and EGI L300120, were isolated from sediment collected from Chaiwopu Lake in Xinjiang, China. The taxonomic position of the two strains was determined using polyphasic taxonomic analysis and phylogenomic analysis. Based on 16S rRNA gene sequence similarities, strain EGI L300112T and EGI L300120 were both closely related to Pelagerythrobacter rhizovicinus AY-3RT and shared the highest sequence identities of 96.2% and 96.3%, respectively. However, phylogenetic analysis based on the 16S rRNA gene and genomes clearly demonstrated that the two strains formed a distinct clade with validly published species of the genus Altererythrobacter. Furthermore, the two strains exhibited distinct phenotypic, physiological and genotypic characteristics that differentiate them from other related type species of the genus Altererythrobacter and related species in the family Erythrobacteraceae. Cells of the two strains were aerobic, Gram-stain negative, non-motile and rod-shaped. Optimal growth conditions for EGI L300112T and EGI L300120 occurred on marine agar 2216 at pH 7 at 30 °C. The major respiratory quinone was Q-10. The detected polar lipids of two strains included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylcholine and unidentified phospholipids. The major fatty acids (>10%) were identified as summed feature 3 (C16 : 1ω7 c/C16 : 1ω6 c) and summed feature 8 (C18 : 1ω7 c). The G+C content of strain EGI L300112T and EGI L300120 was 61.2% and 61.4%, respectively. Based on differential phenotypic and genotypic characteristics of the two strains and related species in the genus Altererythrobacter, the two strains should be classified as representing a new species of this genus, for which the name Altererythrobacter chaiwopuensis sp. nov. is proposed. The type strain is EGI L300112T (=MCCC 1K09432T=KCTC 8712T).

Rhodococcus dendrobeaniae sp. nov., an actinomycete isolated from an Arctic marine invertebrate exhibiting cytotoxic activity, and an emended description of Rhodococcus sovatensis.

A polyphasic study was conducted to establish the taxonomic status of strain T060T, an orange, aerobic, coccoid and non-motile actinomycete, isolated from a marine bryozoan (Dendrobeania sp.) collected in the Barents Sea. Phylogenetic analysis of the 16S rRNA gene sequences revealed Rhodococcus sovatensis DSM 102881T as the closest related species to strain T060T with a similarity of 99.54%. Phylogenomic analysis confirmed a close relationship between T060T and R. sovatensis DSM 102881T, while supporting their distinction. Digital DNA-DNA hybridization and average nucleotide identity values between strain T060T and R. sovatensis DSM 102881T were 26.4 and 84.3%, respectively, supporting the delineation of the isolate as a new species. Genomic characterization of the assembled genomes of T060T and R. sovatensis DSM 102881T showed genome sizes of 5.3 and 4.2 Mbp, with a G + C content of 64.38 and 65.01%, respectively. Genome analysis of strain T060T identified 15 biosynthetic gene clusters (BGCs) with low sequence similarity to known BGCs, indicating its capacity to produce unknown, potentially bioactive secondary metabolites. Furthermore, growth of T060T in eight different media revealed condition-dependent cytotoxic activity. The strongest cytotoxicity was observed for fractionated extracts from T060T grown in half-strength ISP 2 with filtered seawater against the human malignant cell lines MCF7 and A2058, and to a lesser extent against the non-malignant MRC5 cell line, highlighting its biotechnological potential. Based on the data from polyphasic taxonomy studies, it is proposed that strain T060T be classified in the genus Rhodococcus as Rhodococcus dendrobeaniae sp. nov. Additionally, the acquired data of R. sovatensis were used to amend its original description.

Isolation and Taxonogenomic Analysis of Aliiroseovarius pontivivens sp. nov., a Novel Marine Alphaproteobacterium