BIOTECHNOLOGICAL POTENTIAL AND PHYSIOLOGICAL ADAPTATION OF POLY-EXTREMOPHILIC BACILLUS STRAINS ISOLATED FROM THE HYPERSALINE SEBKHAS OF ADRAR, ALGERIA

Abstract

The hypersaline and alkaline sebkhas of Adrar (Algeria) constitute extreme ecosystems that have remained largely unexplored. The objective was to isolate and to characterize various Bacillus strains extracted from these specific environments. Two poly-extremophilic isolates, Bacillus tequilensis (KM9) and Bacillus paralicheniformis (KM2), were identified through the analysis of 16S rRNA phylogeny. Physiological testing demonstrated robust adaptations: Isolate KM9 exhibited a broad salinity range (ranging from 2 to 17.0% w/v NaCl, S_opt 6%) and strict alkaliphily (pH_optimum 9.5, with growth observed up to pH 11.0). In contrast, Isolate KM2 exhibited higher thermal tolerance (T_maximum 50°C, T_optimum 40°C), while maintaining growth up to 20% NaCl and pH 10.5. Functional profiling via API ZYM (Analytical Profile Index ZYM) revealed Isolate KM9’s N-acetyl-β-glucosaminidase activity, whereas Isolate KM2 demonstrated a broad hydrolytic spectrum (including proteases and glycosidases) and potent antimicrobial efficacy against Staphylococcus aureus (25 mm), Pseudomonas aeruginosa (20 mm), as well as showing 50% inhibition of Fusarium oxysporum and Aspergillus flavus. These findings underscore the Adrar sebkhas as untapped reservoirs for diverse Bacillus strains. Their ability to remain active under simultaneous thermal, saline, and alkaline stress underscores their potential as sources of robust extremozymes and biocontrol agents for industrial biotechnology.