Optimization of Green Synthesis of TiO ₂ Nanoparticles by Bacillus velezensis as Antibacterial Agent

Streptococcus mutans ( S. mutans ) being one of the most prevalent pathogenic bacteria, can form biofilms and cause oral infections. The subsequent need is a strong and effective antimicrobial material with minimal side effects to limit biofilm formation and biofilm proliferation from this bacterium. In this study we employed the Taguchi experimental design technique to study the synthesis of TiO ₂ nanoparticles from Bacillus velezensis ( B. velezensis ) and evaluated their ability to inhibit the growth of S. mutans in vitro. Three main parameters influencing synthesis metatitanic acid concentration, glucose concentration, and incubation time were examined and analyzed at three different levels. Antibacterial effectiveness was maximally observed with the nanoparticles synthesized under the conditions of experiment 9 (1.5 mg/mL metatitanic acid, 3 mg/mL glucose and 48 hours incubation). It was observed that these nanoparticles were able to inhibit bacterial growth quite effectively and the bacterial viability was the lowest (0.31 Log₁₀ CFU/mL) with these nanoparticles. With the outlined conditions of production, TiO ₂ nanoparticles demonstrated considerable antimicrobial activity against S. mutans . The study indicates the promising ability of these nanoparticles in clinical therapies for the intervention and prophylaxis of biofilm-associated bacterial infections within the oral cavity.