Abstract: Journal of Agricultural, Earth and Environmental Sciences

Abstract:
The present study aimed to isolate soil bacteria and determine their antibiotic sensitivity susceptibilities. A total of sixty (60) Bacillus species were isolated from the soil samples around the Olusegun Agagu University of Science and Technology (OAUSTECH), Okitipupa, Nigeria. The antibiotic sensitivity test was carried adopting the clinical laboratory standard procedure for agar diffusion method. The test microorganisms were Streptococcus pyogenes, Staphylococcus aureus and Gram negative bacteria such as Pseudomonas aeruginosa, Escherichia coli and Kleb siella pneumonia obtained from the Microbiology Laboratory of the university in Okitipupa. Bacillus isolates that produced large inhibition zones were characterized and identified based on their colonial morphology and bio chemical reactions. The bacteria isolated include Bacillus subtilis, B. licheniformis, B. pumilus B. megaterium and B. sphaericus. Out of the total 60 Bacillus species screened, 50% of the isolates showed no antibiotic sensitivity and with 0.0 mm clear zone, 26.7% of the population exhibited slight inhibition between 1.0 to 5.0 mm clear zones, 15% showed average of between 5.0 to 15 mm zone of inhibition, while 8.3% exerted high antibiotic sensitivity ranging from 15.0 mm to 27.0 mm wide zones of inhibition respectively. The varied antimicrobial activity exhibited by the isolated microorganisms on the test microorganisms demonstrated the potentials of the Bacillus isolates as antimicrobial source. Bacillus subtilis and B. licheniformis showed very large activities against three of the five test microorganisms with activities against both Gram positive and Gram negative bacteria. Bacillus subtilis G8 isolates inhibit Streptococcus pyrogenes, E. coli and K. pneumoniae. It inhibits Streptococcus pyrogenes with up to 27 mm zone of inhibition. Thus, it can be a source of antimicrobials in the treatment of bacteria human pathogens.