Green Synthesis of Silver Nanoparticles Using Lactic Acid Bacteria: Assessment of Antimicrobial Activity

Abstract

The biosynthesis of silver nanoparticles (Ag-NPs) is a new methodology in nanotechnology with a hopeful implementation in medicine, food control, and pharmacy. The objective of the present research was to conduct a green synthesis of Ag-NPs using the cell-free supernatant of Lactobacillus plantarum and Lactobacillus brevis and evaluate their antibacterial and antifungal activities. The production of Ag-NPs was confirmed by the color alteration from yellow to brown. Using the UV-visible spectrophotometer, the biosynthesized Ag-NPs indicated an absorption peak at 410 nm. The transmission electron microscope was used for the determination of the size and morphology of the nanoparticles. Nanoparticles appeared in spherical or polyhedral form, poly-dispersed and their diameter ranged from 5 to 40 nm. The X-ray diffraction analysis exhibited the crystalline nature of the particles with a face-centered cubic (FCC) structure. The biosynthesized Ag-NPs were evaluated for their antimicrobial efficiency using the agar well diffusion method. The antibacterial activity of Ag-NPs was more potent against Gram-negative bacteria than Gram-positive bacteria. Ag-NPs synthesized from Lactobacillus plantarum recorded the maximum activity against Escherichia coli (ATCC® 10536™) and Pseudomonas (ATCC® 27853™) bacteria, while those synthesized from Lactobacillus brevis recorded the maximum activity against Escherichia coli (ATCC® 35218™). Ag-NPs synthesized from Lactobacillus plantarum and Lactobacillus brevis showed antifungal activity against Candida albicans (ATCC® 10231™). The effect of these nanoparticles on Escherichia coli (ATCC® 10536™) was examined and imaged by a transmission electron microscope that indicated damage to the plasma membrane and cell wall. In conclusion, the biosynthesized Ag-NPs have applications as antimicrobial agents in the medicine and food industry.

Chemical characterization, antimicrobial, antioxidant, and cytotoxic potentials of Swietenia mahagoni

“…Standard antibiotics (1 mg/mL ampicillin) were used as a positive control, and methanol was used as a negative control to determine the sensitivity of the strains. The inoculated plates were incubated at 37 °C for 24 h (Syame et al 2020 ). The inhibition zone diameter was measured using a ruler to determine the antibacterial activity.…”

Biosynthesized Silver Nanoparticles Derived from Probiotic Lactobacillus rhamnosus (AgNPs-LR) Targeting Biofilm Formation and Quorum Sensing-Mediated Virulence Factors

“…Observations were made of the colour change of AgNPs after 24 h of synthesis. As part of the characterization of the AgNPs-LR, UV-Vis, FTIR and TEM analysis were performed [ 31 ].…”

“…In order to characterize AgNPs-LR, a spectrophotometric analysis was performed as a first step. With a resolution of 1 nm, AgNPs-LR were scanned in the range of 300 to 700 nm [ 31 ]. The UV-Vis analysis was further used to determine the size of AgNPs-LR using Haiss equation, d = ln((λSPR − λ0)/L1)/L2.…”