Molecular identification, antibacterial activity, and production of hydrolytic enzymes by halotolerant bacterium Streptomyces sp. ESM2-25 GTF strain isolated from extreme environment in north-east of Algeria

Abstract

The aim of this study is to establish the taxonomic position of the halotolerant bacterium ESM2-25 GTF strain isolated from the extreme environment of El-Mellah lagoon water, which is situated in the city of El-Kala in the northeast of Algeria and to study its phenotypic characteristics, antibacterial activity against several pathogenic bacteria, and hydrolytic enzymes production. The novel bacterium ESM2-25 GTF strain was isolated from water samples by the dilution agar plating method using the starch-casein medium, screened in vitro for its hydrolytic enzymes production and antibacterial activity. The phenotypic and molecular characteristics show that the strain ESM2-25 GTF belongs to the genus Streptomyces. However, the comparison of the morphological and physiological characteristics of the strain ESM2-25 GTF with those of the nearest species showed significant differences. This strain showed an antibacterial activity against Bacillus subtilis subsp. spizizenii CIP 106094, Escherichia coli ATCC 29522, Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 29213 and S. aureus MRSA ATCC 43300, while it is not active against Pseudomonas aeruginosa ATCC 27853. Furthermore, the strain ECM2-25 GTF was able to produce different hydrolytic enzymes such as lipase, protease, amylase, catalase, and gelatinase, which have applications in the field of food and industry. The interesting antibacterial activity of the strain ESM2-25 GTF against pathogenic bacteria and hydrolytic enzymes production indicate the importance of the exploitation of marine actinomycetes for biotechnological applications and the discovery of new antibacterial molecules and could encourage further research on the bioactive molecules secreted by this strain.