Fourteen poly-extremophilic bacterial strains were isolated from saline and salt-affected soils in Egypt. Isolation of the strains was done after incubation at 55°C on two different agar media supplemented with 10% NaCl and adjusted at pH 10 (thermohaloalkali philic/tolerant). The isolated extreme bacterial strains were screened for their enzymatic potential. They showed high amylolytic and proteolytic activities but less cellulosic or pectinolytic activities. The fourteen isolates were characterized by studying their morphological, physiological and biochemical characters. Based on their phenotypic characteristics, twelve strains were tentatively identified to four different Gram-positive rod-shaped genera namely, Alkalibacillus, Gracilibacillus, Halobacillus and Piscibacillus, and the other two strains could not be identified. Then, the two most active strains with broad spectrum enzymatic activities, designated M201 and M610, were subjected to phylogenetic analyses of the 16S rRNA gene sequences. The phylogenetic results revealed that strain M201 belongs to genus Gracilibacillus and strain M610 belongs to genus Piscibacillus. The results indicated that the two strains could be classified as new species.
Key words: Extreme bacteria, salt-affected soils, enzymatic potential, characterization, phylogenetic analysis.