Paper Title
Biosynthesis of Silver Nanoparticles by Marine Bacteria and Their Synergistic Effect with Antibiotics Against Pathogenic Bacteria

In the current study, 36 silver resistant bacterial isolates were isolated from 18 samples from different environmental sources of red sea cost at Jeddah city, , Saudi Arabia. Among These isolates, bacterial strain BM was selected on the basis of its ability to produce stable extracellular silver nanoparticles ( AgNPs). Biochemical and Molecular characterization of this isolate indicated that BM strain is belonged to Vibiro sp. and identified as V. alginolyticus. BGRW was found to be highly resistant to silver ions up to 5 mM. The biosynthesis of SeNPs was monitored by UV–Visible spectrum that showed surface plasmon resonance (SPR) peak at 408 nm. Further characterization of synthesized AgNPs was carried out using the XRD, TEM and FTIR spectroscopy. TEM and XRD analysis revealed that the AgNPs synthesized by BGRW was spherical in shape with a size range of 10-27.5 nm with average 18.8 nm. FTIR spectroscopy confirmed the presence of proteins as the stabilizing agent surrounding the nanoparticles. Six antibiotics were investigated to explore their synergistic effect when combined with AgNPs against various pathogenic bacteria. All tested antibiotics showed synergistic inhibition against growth of the pathogenic bacteria. The biocide actions of SeNPs on Gram-negative and Gram-positive pathogens were studied using SEM. The results showed damage, blebs, fusion, clumps and randomly distribution of the cell wall of the tested microbes resulting the death of cells Key Words - Marine bacteria, Vibrio alginolyticus, AgNPS, antimicrobial, Pathogenic bacteria