Study of exopolysaccharids production and antimicrobial activity in Actinobacteria strains isolated from saline soils

Abstract

This study aimed to isolate and characterize Actinobacteria strains from saline soils, focusing on their exopolysaccharide (EPS) production and antimicrobial activity against four microorganism, including Escherichia coli and Staphylococcus aureus, as well as fungal (mold) strains such as Penicillium.sp and the yeast strain Saccharomyces cerevisiae. The research was conducted at the microbiology laboratory of Zian Achour University of Djelfa, using standard methods for Actinobacteria isolation, characterization, and antimicrobial testing. Soil samples were collected from a saline site 'sabkha' area in Mosran, Djelfa, and Actinobacteria were isolated using a dilution series and selective media. The isolated strains were purified and subjected to salt, temperature, and pH tolerance tests. Cultural and morphological characteristics were analyzed, and the antibacterial activity of the strains was determined. One of the key objectives of this study was to investigate the production of extracellular polysaccharides (EPS) in the chosen isolated Actinobacteria strains H3, H8, and H13. EPS production is a crucial trait exhibited by many bacteria, including Actinobacteria, and it serves various biological functions. To assess EPS production, the Actinobacteria strains were cultivated in specific media (ISP2 liquid media) known to promote EPS production, and the amount of EPS produced was quantified. The yield of EPS production for all three samples (H3, H8, and H13) was approximately 0.202%. In terms of antimicrobial activity, the isolated Actinobacteria strains were evaluated against four microorganism. Antimicrobial testing was performed using the perpendicular streak method and the agar well diffusion method. The results revealed different degrees of antimicrobial activity exhibited by the Actinobacteria strains. Some strains demonstrated antimicrobial activity against all four tested microorganisms, inhibiting the growth of pathogens, while other strains showed activity specific to certain microorganisms. The antimicrobial activity of the Actinobacteria strains was observed through the formation of inhibition zones around the perpendicular streaks and agar wells. The findings of this study shed light on the potential of Actinobacteria from saline soils for biotechnological applications. By elucidating their antimicrobial activity against four microorganisms, the Actinobacteria show promise as a source of novel antimicrobial agents. Furthermore, the investigation of EPS production in the Actinobacteria strains contributes to our understanding of their biological activities and opens avenues for further research in the field of microbial biotechnology. This research emphasizes the significance of studying Actinobacteria from saline soils, which represent a unique ecological niche with untapped microbial diversity. The implications of this study extend to various fields, including biotechnology, agriculture, and pharmaceutical sciences, where the search for novel bioactive compound and antimicrobial agents is of paramount importance.