Synthesis of stabilized silver nanoparticles with exopolysaccharides of lactic acid bacteria and evaluation of its antimicrobial activity

TORINO MARIA INES; RODRÍGUEZ CECILIA; REY VALENTINA; BORSARELLI CLAUDIO; ESPECHE TURBAY BEATRIZ; DORADO RITA DANIELA

Salta

Congreso; LV Annual SAIB Meeting; 2019

Sociedad Argentina en Bioquímica y Biología

The development of new nanomaterials (NM) to be used in antimicrobial therapies, are currently an alternative to conventional antibiotics, which present multiresistance. Silver nanoparticles (AgNP) are used as antimicrobial agents because are able to release silver ion (Ag+), damage the cell envelope or interact with intracellular essential components for microorganism functioning. AgNP synthesis requires stabilizing agents, and different types of molecules have been used with this porpoise, such as proteins, among others. NM are intended not only to exert a deleterious effect on bacteria, but also that these one be biocompatible.Lactic acid bacteria (BAL) are ubiquitous bacteria primarily used in food industry, because of an extra value added to food. Some of them are able to form exopolysaccharides (EPS) as a metabolism product, this being itself a bioactive compound. Considering these, EPS were used as stabilizing agents in AgNP synthesis.Weissella cibaria CRL 11 EPS (EPSCRL11) produced from solid medium was isolated, purified and lyophilized. The photoreductive synthesis of AgNP was completed using EPS as a stabilizing agent (AgNP @ EPSCRL11), obtaining stable nanoparticles, which were characterized by UV-Vis and infrared (FT-IR) spectroscopy, ligth dimanic scaterring (DLS), potential Z (pZ) and transmission electron microscopy (TEM). AgNP @ EPSCRL11 has a size of 12 ± 2 nM, and a concentration of 3.77 nM. Antinimicrobial (AA) activity was evaluated on Gram positive (Staphylococcus aureus ATCC 25923, Bacillus sp., Micrococcus luteus) and negative (Escherichia coli O157H7; Serratia marcescens, Klebsiella pneumoniae) strains. Agar diffusion technique was employed, demonstrating activity on gram-positive strains. The minimum inhibitory concentration (MIC) in the sensitive strains was determined, being possible to obtain it for Micrococcus luteus (MIC = 1.26nM).Subsequent studies carried out by increasing the concentration of the EPS, and consequently the concentration of the NP, demonstrated a higher AA.Our results show that is necessary not only to obtain new potentially active antimicrobial agents, but also their respective AA assessment on strains of interest.