What question did this study set out to answer?

This study aims to characterize a novel halotolerant Actinomycetota strain isolated from a Moroccan hypersaline ecosystem.

March 31, 2026Open Access

Genome sequencing and comparative analysis of Nocardiopsis moroccensis sp. nov., a halotolerant Actinomycetota from Moroccan hypersaline ecosystem

Key Points

This study aims to characterize a novel halotolerant Actinomycetota strain isolated from a Moroccan hypersaline ecosystem.
Isolated strain ZS3416R2A from saline soil in Lake Zima, Morocco.
Conducted phylogenetic analysis using 16S rRNA gene sequences.
Performed whole-genome sequencing to analyze genomic features.
Carried out comparative analyses to identify gene families and biosynthetic clusters.
Conducted chemotaxonomic characterization including menaquinones and fatty acids.
Confirmed strain ZS3416R2A as a novel species closely related to Nocardiopsis terrae.
Provided genomic metrics: ANI 95.07%, dDDH 66.4%, AAI 95.87%, and POCP 82.4%.
Demonstrated unique gene families and biosynthetic clusters in ZS3416R2A.
Observed phenotypic adaptations such as broader salinity and temperature tolerance.
Identified predominant menaquinones and fatty acids characteristic of the strain.

Abstract

Saline and arid ecosystems are recognized as promising reservoirs of novel Actinomycetota with unique adaptations and secondary metabolic potential. In this study, a halotolerant Actinomycetota strain, designated ZS3416R2A, was isolated from saline soil in the hypersaline wetland of Lake Zima, Morocco. Phylogenetic analysis based on the 16S rRNA gene sequence showed 99.03% similarity to Nocardiopsis terrae DSM 45157 T, indicating close affiliation with the genus Nocardiopsis. Whole-genome sequencing revealed a 6.1 Mb circular chromosome with a G + C content of 70.48% and 5,855 coding sequences. Genome-based metrics (ANI 95.07%, dDDH 66.4%) supported its classification as a novel species distinct from N. terrae, while AAI (95.87%) and POCP (82.4%) confirmed its placement within the genus. Comparative analyses revealed unique gene families, biosynthetic gene clusters, and regions of genomic plasticity in strain ZS3416R2A. Phenotypically, strain ZS3416R2A grew over a broad range of salinity (0–10%), temperature (16–37 °C), and pH (7.0–8.0), and formed denser aerial mycelia than strain DSM 45157 T, reflecting adaptation to the arid saline environment of Lake Zima. Chemotaxonomic characterization identified MK-10(H6), MK-10(H4) and MK-9(H4) as predominant menaquinones, iso-C16:0 and 10-methyl-C18:0 as major fatty acids, and diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, and phosphatidylinositol as major polar lipids. Based on this polyphasic evidence, strain ZS3416R2A represents a novel species within the genus Nocardiopsis, for which the name Nocardiopsis moroccensis sp. nov. is proposed. The type strain is ZS3416R2AT (= CCMM B1332T = DSM 120542 T).

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