ISOLATION AND SCREENING OF ANTIBIOTIC PRODUCING BACILLUS SPECIES FROM SOIL SAMPLES IN OKITIPUPA, NIGERIA

Abstract

This study was carried out to isolate soil Bacillus species with antibiotic production features and determine their antibiotic sensitivity pattern around the Olusegun Agagu University of Science and Technology (OAUSTECH), Okitipupa, Nigeria. The antibiotic sensitivity test was carried out using Agar diffusion method. The test microorganisms were Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae from the Microbiology Laboratory of the University. Bacillus isolates were able to produce large inhibition zones, they were characterized and identified based on their colonial morphology and biochemical test. The isolates identified are Bacillus subtilis, B. licheniformis, B. pumilus, B. megaterium and B. sphaericus. Out of the total 60 Bacillus species screened, 50% of the isolates demonstrated no antibiotic sensitivity and with 0.0 mm inhibition zone, 26.7% of the population exhibited slight inhibitions of 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 of 15.0 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 antibiotics or antimicrobial sources. Bacillus subtilis and B. licheniformis showed very large activities against three each 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. Future studies are required to further confirm and characterized the antibiotic feature of the antimicrobials produced. Bacillus species isolates have demonstrated their potentials as a possible source of antibiotics in the treatment of microbial human infections. Future studies are required to further confirm and characterize the antibiotic feature of the antimicrobials produced.