Bactericidal Properties of Bacillus Subtilis Nanoparticles Against Selected Human Pathogens

The use of biologically synthesized nanoparticles has been an area of research interest in recent times. Due to the high rate of bacterial resistance to antibiotics, there is a need to search for a more potent alternative to ineffective antibiotics. This study aims to evaluate the antibacterial effects of silver nanoparticles synthesized by Bacillus subtilis against Pseudomonas aeruginosa and Staphylococcus aureus. Silver nanoparticles were obtained by dissolving 0.842 gram of AgNO3 silver nitrate into 100ml of B. subtilis in Mueller Hinton broth. The antibacterial susceptibility of the nanoparticles formed was carried out using standard methods. Comparative antibacterial test was also carried out using standard antibiotics The multiple antibiotic resistance index were also determined. The zones of inhibition were 29 and 12 mm against Staphylococcus aureus and Pseudomonas aeruginosa respectively after 8 hrs of nanoparticle synthesis. The antibiotic susceptibility test using standard antibiotics revealed that S. aureus was sensitive to only Erythromycin and ofloxacin with a zone of inhibition of 15mm and 9mm respectively while P. aeruginosa was sensitive only to ofloxacin. The Multiple resistance index (MARi) shows P aeruginosa to have MARi of 0.9 while S, aureus has MARi of 0.82. The result indicated that B. subtilis nanoparticles presented better antibacterial properties than standard antibiotic and can be explored as a candidate for drug production to fight bacterial resistance to antibiotics.