Scilight Press

Twenty-five soil samples were collected from five different sites. Three isolates were identified for their antibacterial activity against pathogenic bacteria through primary screening protocol and on their inhibitory activity against the pathogenic bacteria. These were tested for their antibacterial activity through secondary screening protocol. These isolates were identified and diagnosed using many physiological, biochemical tests and amplification of 16S rRNA gene sequence. The isolates were identified as Bacillus subtilis (B1) and two Bacillus polymyxa (B4) and (B7). These had high inhibitory activity against Escherichia coli and Staphylococcus aureus with inhibition zone reaching to 34 mm and less activity against Klebsiella pneumonia and Pseudomonas aeruginosa. B1 isolate was characterized by greater inhibitory activity against pathogenic bacteria. The antibacterial agents that produced by these isolates were characterized by three different methods. First : The ultraviolet spectroscopy (UV) for measuring the λmax, the results showing the range of this assay from 234 to 350 nm. Second : Infrared spectroscopy (FT-IR) in the range from 400 to 4000/cm. Third : Liquid chromatography by mass spectrometer analysis. The effect of temperature on the growth of the two isolates showed that they were developing well in temperature 40 and 45°. Both isolates were unable to grow at a temperature of 5°C and the effect of salinity on the growth of the isolates showed that they were developing well in 3% NaCl concentration. Only B1 was able to grow till 6% NaCl concentration, while both isolates were unable to grow at 10% concentration of sodium chloride. Activity of antioxidant was determined by using DPPH (2,2-diphenyl-2-picrylhydrazyl). The extract bacterial had the highest antioxidant activity with median effective dose (IC50) as 5.24±8.0 µg/ml.