Silver Nanoparticles Biosynthesis using Mixture of Lactobacillus sp. and Bacillus sp. Growth and their Antibacterial Activity

Biosynthesis of nanoparticles is characterized by ease, low cost, and speed as it is considered environmentally friendly. Recently, the employ of bacteria in the bioformation of nanoparticles has increased. In this study, AgNPs were created by the mixture of Lactobacillus sp. and Bacillus sp. growth and evaluated the biological activities of AgNPs against multidrug resistant bacteria. Bacillus sp was isolated from soil samples while Lactobacillus sp was isolated from raw milk in Dhamar Governorate – Yemen. The AgNPs were characterized by UV-visible, XRD, FTIR, and TEM. The antibacterial activities of the AgNPs were examined according to the modified Kirby Bauer disk diffusion method. The antibacterial assay was used against multidrugs resistant Staphylococcus aureus and Pseudomonas aeruginosa. The results indicate that the use of a mixture of bacteria in biosynthesis was faster and more effective than the use of a single bacterium. We observed abroad peaks located between 410 and 430 nm for the silver nanoparticles biosynthesized by bacteria due to its surface plasmon resonance absorption band. Nine peaks were detected on the XRD at 2θ values of 27.87 º , 32.32 º , 38.23 º , 44.44 º , 46.22º, 54.8 º , 57.34 º , 64.63 º and 77.39, which correlate to reflection of (111), (200), (220) and (311) respectively by XRD. FTIR results have proven the presence of a capping protein in silver nanoparticles from growth bacteria, which can be responsible for the synthesis and stability of AgNPs. TEM micrograph showed the size of the silver nanoparticles is between 4.65 – 22.8 nm and have spherical shape. In our study, the antibacterial activity of AgNPs synthesized by bacteria was higher against Staphylococcus aureus than Pseudomonas aeruginosa. AgNPs synthesized by a mixture of Lactobacillus sp. and Bacillus sp. growth had greater antibacterial activity than silver nanoparticles synthesized by each bacterium separately. More studies are needed to synthesis nanoparticles by a mixture of different types of bacteria to produce nanoparticles better and faster.