Abstract
Biosynthesis of AgNPs is a new approach in the field of nanotechnology with optimistic implementation in medicine, food control, and pharmacology. In this study, the silver nanoparticles were produced by Lactobacillus gasseri filtrate. The production of AgNPs was confirmed by the color change from yellow to brown. Using UV visible spectrophotometer at 424 nm wavelength, and X-ray diffraction, it was found that the size of the synthesized particles was 58.5 nm after applying Scherrer’s equation. The inhibitory activity of silver nitrate on the growth of some pathogenic isolates was studied Staphylococcus haemolyticus Gram positive, and Klebsiella pneumoniae Gram negative. The highest inhibitory diameter was 14.6 mm at 100% concentration (stock) against Staphylococcus haemolyticus bacteria was followed by that of Klebsiella pneumoniae bacteria with an average inhibition zone diameter reached 13.6 mm at 100% concentration. The highest effect was of AgNPs on the growth of Staphylococcus haemolyticus bacteria, as it found the average diameter of the inhibition zone reached to 29.3 mm, followed by Klebsiella pneumoniae with the average diameter of the inhibiting zone it was 22.6 mm at 100% concentration (stock). This study showed AgNPs have more antibacterial activity against Gram positive bacteria than Gram negative bacteria. The importance of this study lies in testing the effectiveness of by Lactobacillus gasseri bacteria in the biosynthesis of silver nanoparticles and studying their antibacterial activity on pathogenic bacteria.
Highlights
The problem of antibiotic resistance has become a major concern for clinicians and for all in their quest to treat and prevent infections caused by microorganisms that were previously thought to be eliminated with antimicrobials
This study showed AgNPs have more antibacterial activity against Gram positive bacteria than Gram negative bacteria
The silver nanoparticles were synthesized using a filtrate of L.gasseri bacteria; 10ml of culture filtrate was mixed with 90 ml of 5 mM silver nitrate solution and incubated at room temperature for 48 hours
Summary
The problem of antibiotic resistance has become a major concern for clinicians and for all in their quest to treat and prevent infections caused by microorganisms that were previously thought to be eliminated with antimicrobials. Lactobacilli grow on a variety of media including MRS (Man, Rogosa, Sharpe agar) where they grow as white colonies, usually, mucous Lactobacillus consists of more than 170 species and 17 subspecies that have been properly propagated and have a good standing in the nomenclature In humans, they are naturally present in the vagina and gastrointestinal tract but can be opportunistic pathogens occasionally like L.rhamnosus , L.fermentum, L.paracasei, L.oris, L.gasseri, L.iners, and L.salivarius [7]. With the Appearance of nanotechnology, it became possible to produce nanoscale silver [9, 10] It is used as a more effective antibacterial compared with antibiotics, as it provides a good bond with the bacteria through the cell membrane and penetrates the membrane into the bacterial cell, and it does not have any activity in its normal state, but by ionizing it with the presence of water or tissue fluids, it leads to the release of bioactive silver ions. The aim of this study performs biosynthesis of AgNPs using L.gasseri bacterial filtrate with silver nitrate solution and study the inhibitory effect against pathogenic bacteria (S.haemolyticus and K.pneumoniae), comparing the antibacterial activity of silver nitrate and silver nanoparticles
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