Investigating the antibacterial effect of Bacillus subtilis natto on human intestinal pathogens

Treatment of diarrhea caused by bacteria is a progressing phenomenon in which probiotics play an essential role. The aim of this study is to investigate the antibacterial effect of the probiotic Bacillus subtilis natto on a number of common pathogens of the digestive system. In this study, Bacillus subtilis natto ATCC G۸S۳ strain was selected as a probiotic and its antimicrobial effect on four gastrointestinal pathogens including Bacillus cereus ATCC ۱۱۷۷۸, Salmonella typhimurium ATCC ۱۴۲۹, Shigella flexneri ATCC ۱۱۲۲۲ and Escherichia coli ATCC ۲۵۹۲۲ was investigated. In order to detect the antimicrobial activity of Bacillus subtilis natto, various methods such as agar well diffusion, disc diffusion, MIC and MBC were used based on microbiology standards and with four replications. In the agar well diffusion method, among the four pathogens, Bacillus subtilis natto showed an antimicrobial effect only on the pathogen Escherichia coli, a non-growing halo with a diameter of ۱۰ mm but this probiotic did not show antibacterial effect on Bacillus cereus, Salmonella and Shigella pathogens. In the disk diffusion method, Bacillus subtilis natto did not show antimicrobial effect on any of the pathogens of this research. MIC for Escherichia coli pathogen was ۵۰, while no antibacterial effect was observed on Bacillus cereus, Salmonella and Shigella pathogens. MBC results showed that this probiotic had no lethal effect on the studied bacteria. Bacillus subtilis natto ATCC G۸S۳ is safe and resistant as a probiotic and it was able to show inhibitory results on Escherichia coli pathogen.

کلیدواژه ها:

Probiotic ، Bacillus subtilis ، Diarrhea ، Gastrointestinal pathogens ، Antibacterial