Antimicrobial Activity of Bacillus Persicus 24-DSM Isolated from Dead Sea Mud

Dead Sea is a hypersaline lake with 34% salinity, gains its name due to the absence of any living macroscopic creatures. Despite the extreme hypersaline environment, it is a unique ecosystem for various halophilic microorganisms adapted to this environment.

Halophilic microorganisms are known for various potential biotechnological applications, the purpose of the current research is isolation and screening of halophilic bacteria from Dead Sea mud for potential antimicrobial applications.

Screening for antagonistic bacteria was conducted by bacterial isolation from Dead Sea mud samples and agar plate antagonistic assay. The potential antagonistic isolates were subjected to biochemical characterization and identification by 16S-rRNA sequencing. Among the collected isolates, four isolates showed potential antagonistic activity against Bacillus subtilis 6633 and Escherichia coli 8739. The most active isolate (24-DSM) was subjected for antagonistic activity and minimal inhibitory concentration against different gram positive and negative bacterial strains after cultivation in different salt concentration media. Results: The results of 16S-rRNA analysis revealed that 24-DSM is very closely related to Bacillus persicus strain B48, which was isolated from hypersaline lake in Iran.

Therefore, the isolate 24-DSM is assigned as a new strain of B. persicusi isolated from the Dead Sea mud. B. persicusi 24-DSM showed higher antimicrobial activity, when it was cultivated with saline medium, against all tested bacterial strains, where the most sensitive bacterial strain was Corynebacterium diphtheria 51696.