Diversity and characterization of culturable haloalkaliphilic bacteria from two distinct hypersaline lakes in northern Egypt

Abstract

Soda lakes characterized by salinity and elevated pH, these lakes represent a vast reservoir of novel microbial diversity of potential applications. In this article, two distinct salt lakes in northwestern Egypt were explored for the diversity of cultivable aerobic haloalkaliphilic bacteria. Physicochemical analyses revealed that samples possessed the characteristic features of alkaline hypersaline lakes (high pH, high Na+, and Cl− content with low Mg+2). The phenotypic characterization showed great diversification between members of the same genus. They were characterized phenotypically based on their cell and colony morphology, production of extra-cellular enzymes, some metabolic activities and antibiogram profile. Phylogenetic analysis was performed using 16S rRNA sequence. All strains were haloalkaliphilic belonging to phylum Firmicutes. They were affiliated to the genera Alkalibacillus, Salinicoccus, Gracilibacillus, Thalassobacillus, Halobacillus, Staphylococcus, and Bacillus. Surprisingly, Thalassobacillus species were only isolated from the sediment of Marsa-Matrouh lake (MML), while members of the genera Alkalibacillus, Salinicoccus and Staphylococcus were isolated from the sediment of Al-Hamra lake (AHL). Members of the genus Gracilibacillus were among the common community of the two lakes.