Whole-genome sequencing of Nocardiopsis sp. B33, an alkali-halo-tolerant and moderately thermotolerant plant growth-promoting strain from Algerian Saharan soil: an in vitro and in silico study

Abstract

[EN]The Sahara, the world's largest hot desert, poses extreme challenges for microbial survival due to high temperatures and aridity, making it a valuable source of novel secondary metabolites. In this study, strain B33 was isolated from El Oued in the Algerian Sahara and assessed through preliminary in vitro assays and whole-genome sequencing. The strain showed weak antifungal activity against Penicillium expansum B831P, exhibited indications of hydrolytic enzyme production in plate-based assays, and grew under broad conditions (0–7 % NaCl, pH 7–11, 20–45 °C), reflecting adaptation to Saharan extremes. The complete genome of this Saharan isolate was sequenced and analyzed; no plasmids were detected, and multi-platform annotation provided a comprehensive overview. Although closely related to Nocardiopsis algeriensis DSM 45462ᵀ, the strain displayed some phenotypic and genomic differences. Genome mining predicted 10 biosynthetic clusters potentially associated with diverse bioactivities, suggesting avenues for further experimental validation. The novelty of this study lies in combining preliminary physiological assays with genome analysis to provide insights into the adaptation and putative biotechnological potential of Nocardiopsis sp. B33, while recognizing that quantitative enzyme assays and application-oriented studies remain necessary to substantiate its functional relevance.