BIOSYNTHESIS OF BIOACTIVE SILVER NANOPARTICLES BY Actinomycetes sp. AND ITS APPLICATION AS ANTIBIOTICS AGAINST SOME SELECTED BACTERIAL PATHOGENS

Abstract

Nanotechnology is the novel science that deals with the production, manipulation and application of nano-materials. Nanoparticles can be produced by physical, chemical, or biological methods. Of these methods, biological is the most preferred due to its eco-friendly nature, and the fact that it is cheaper to carry out. This study is aimed at isolating, screening, and synthesizing silver nanoparticles using Actinomycetes sp. from MTU dumpsite. The isolates were screened for antibiotics production. The best isolate was identified using morphological and biochemical characterizations. Biosynthesis of silver nanoparticles using the selected isolate was carried out. Characterizations of the biosynthesized silver nanoparticles (AgNPs) using visual observation, UV-spectrophotometer, and FT-IR spectroscopy were investigated. The produced AgNPs was used as an antibacterial agent against five selected pathogenic bacteria including pathogenic Escherichia coli, pathogenic Staphylococcus aureus, Proteus mirabilis, Salmonella enterica, and Enterococcus faecalis. Out of the 13 bacterial isolates, only seven possessed antibacterial activities, out of which, isolate MDC4 and MDN9 identified as Actinomycetes sp were able to synthesize AgNPs. Colour change from yellow to dark brown, and 400 nm surface plasmon resonance (SPR) peaks between 24 to 72 hours were obtained. FT-IR showed 15 peaks with ten functional groups contributing to the synthesis of AgNPs. The biosynthesized AgNPs by the two isolates showed improved inhibitory effect against the selected pathogenic bacteria compared to the bacterial extract. Isolate MDC4 showed better inhibitory activity against pathogenic bacteria compared to MDN9. The biosynthesized AgNPs by MDC4 showed improved inhibitory effect compared to the bacterial extract, and chloramphenicol antibiotics against S. enterica 17, 15 and 0 mm), S. aureus (14, 13 and 11 mm), E. coli (19, 16 and 11 mm), Proteus sp. (27, 0 and 0 mm) and E. faecalis (13, 0 ad 0 mm) respectively, while that of MDN9 were S. enterica (15, 0 and 0 mm), S. aureus (12,0 and 0 mm), E. coli (45, 12 and 30 mm), Proteus sp. (no zones) and E. faecalis (no zones). Isolate. Therefore, MDC4 isolate can be used for antibiotics production on a larger scale.