New salt-tolerant Streptomyces species discovered in Morocco’s Lake Zima

A halotolerant bacterium isolated from the saline waters of Lake Zima in Morocco has been identified as a previously unknown species within the genus Streptomyces. Based on this combined evidence, the researchers propose the name Streptomyces zimensis sp. nov., with strain ZE1316R2Aᵀ serving as the type strain (CCMM B1331ᵀ = DSM 120541ᵀ).

Members of the phylum Actinomycetota, to which the new species belongs, are widely distributed across diverse environments and are well known for their metabolic versatility and their capacity to produce bioactive compounds. The isolation of a novel Streptomyces from a saline lake expands current knowledge of Streptomyces diversity associated with saline environments.

This analysis placed strain ZE1316R2Aᵀ firmly within the genus Streptomyces and showed its highest sequence similarity with S. albidoflavus DSM 40455ᵀ, at 99.71%.

Genome-based indices provided the decisive evidence for distinguishing the new strain. Average nucleotide identity values, calculated as ANIb = 94.84% and ANIm = 96.09%, and digital DNA-DNA hybridisation, which returned 64.9%, all fell below the thresholds conventionally used to delineate bacterial species. Together, these figures support the conclusion that strain ZE1316R2Aᵀ represents a separate species rather than a variant of S. albidoflavus or another close relative.

The draft genome of the strain measures 7.41 Mb with a G+C content of 73.26 mol% and comprises 6,464 coding sequences. Annotation revealed the presence of strain-specific genomic regions and biosynthetic gene clusters, the genetic modules that in Streptomyces species often encode the production of bioactive secondary metabolites. Comparative analyses highlighted both a conserved core genome and a substantial accessory genome component, reflecting genomic differentiation of the new species relative to closely related taxa and underscoring the genomic diversity present even among closely related Streptomyces.

Phenotypic and chemotaxonomic characteristics were consistent with assignment to the genus Streptomyces while supporting the differentiation of the strain at the species level.

Annotation of the draft genome revealed the presence of strain-specific genomic regions and biosynthetic gene clusters in S. zimensis.

The study, published open access in Annals of Microbiology on 29 August 2026, was carried out by Ez-Zahra Oubassou, Soukaina Oudchaira, Valérie Cognat, Abdelmalek Alioua, Florence Arsène-Ploetze, Mathieu Erhardt, David Pflieger, Alexandre Berr and Mustapha Barakate.

Subject of Research: Taxonomic description of the novel halotolerant bacterium Streptomyces zimensis isolated from saline Lake Zima in Morocco

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

Article References: Oubassou, E.-Z., Oudchaira, S., Cognat, V., Alioua, A., Arsène-Ploetze, F., Erhardt, M., Pflieger, D., Berr, A., & Barakate, M. (2026). Polyphasic and genomic characterisation of Streptomyces zimensis sp. nov., a halotolerant Actinomycetota from the Saline Lake Zima in Morocco. Annals of Microbiology. https://doi.org/10.1186/s13213-026-01871-9

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DOI: 10.1186/s13213-026-01871-9

Keywords: Streptomyces zimensis, Actinomycetota, halotolerant bacteria, Lake Zima, Morocco, polyphasic taxonomy, average nucleotide identity, digital DNA-DNA hybridization, biosynthetic gene clusters, saline environments, 16S rRNA, microbial diversity