Production and Characterization of Extremolytes from Radioresistant Bacteria of Garam Chashma, Chitral, Pakistan

Abstract

Radioresistant bacteria thrive in extreme environments having lethal radiations. The metabolites (extremolytes) produced by such bacteria have a major role in their survival in such hostile environments. This research study aims to isolate UV resistant bacteria from Garam Chashma, evaluate the biological activities of the extremolytes extracted from these bacteria and to characterize those extremolytes. Out of 7 bacterial strains isolated from the collected samples, 2 strains (GC-3 and GC-5) were selected. Strain GC 3 was brown pigmented while strain GC-5 was orange pigmented. Strain GC-3 showed 63.66% survivability against 4.1×10³ J/m² dose of UV radiations, 51.36% survivability against 80 mM H₂O₂ and 62% survivability against 50 µg/ml of Mitomycin C. Strain GC 5 showed 67.66% survivability at 4.11×10³ J/m² dose of UV radiations, 55.56% survivability at 60 mM H₂O₂ and 69% survivability against 30 µg/ml of Mitomycin C. Crude extracts of both strains were purified through silica gel column chromatography. Acetone fraction of strain GC-3 and chloroform fraction of strain GC-5 exhibited maximum radical scavenging activities, 67.2% and 51.9% respectively. Purified extract of strain GC-3 showed 77.3% inhibition of lipid peroxidation, 65.2% inhibition of protein oxidation and 49% inhibition of hemolysis. Purified extract of strain GC-5 showed 66.4% inhibition of lipid peroxidation, 57.8% inhibition of protein oxidation and 45% inhibition of hemolysis. Extracts of both strains exhibited 90% cytotoxicity at 100 µg/ml as well as protected the plasmid DNA against oxidative damage. Total phenolic content of the cellular extract of strain GC-3 and GC-5 was 35.68 mg GAE/g and 22.26 mg GAE/g respectively. Total flavonoids content of the cellular extract of strain GC-3 and strain GC-5 was 2.3 mg QE/g and 2.1 mg QE/g respectively. Extracts of both strains exhibited excellent antibacterial and antifungal activities. Extracts of both strains were characterized via Thin layer chromatography (TLC) and Fourier Transform Infrared Spectroscopy (FTIR). The results concluded that extracts of both radioresistant strains (GC-3 and GC-5) possess excellent antioxidant and radioprotective properties.