Isolation, screening, and molecular identification of culturable halophilic bacteria with enzymatic and antimicrobial potential from the saline soils of Arzew salt lake, Algeria.

Abstract

Halophilic microorganisms from extreme environments are increasingly recognized as promising sources of industrial enzymes and antimicrobial compounds. However, many saline ecosystems remain unexplored. In this study, the bacteriological profile of the extreme salt lake of Arzew (Oran, Algeria) was investigated for the first time. Twenty-nine halophilic bacterial strains were isolated from five saline soil samples around the lake and were preliminarily screened for the production of nine industrially relevant enzymes and antimicrobial activities. The enzymatic screening revealed that 69% of the isolates showed single or combined hydrolytic activities, with gelatinase, protease, inulinase, and lipase activities being the most prevalent. The antimicrobial screening showed significant activity against Gram-positive pathogens, Aspergillus niger, Fusarium sp., and Phytophthora infestans. Four of the most potent strains were selected for further phenotypic and molecular characterization. Based on 16S rRNA gene sequencing, the results showed that three isolates belonged to the genus Streptomyces and one representative isolate to the Nocardiopsis genus. Both phylotypes demonstrated tolerance to wide ranges of salt, pH, and temperature. Notably, isolate O61 displayed a distinct phylogenetic position, suggesting its potential affiliation as a novel Streptomyces species. These results provide a baseline microbial resource discovery from an underexplored Algerian hypersaline environment and highlight promising candidates for future detailed characterization for biotechnological applications.