Synergic effect of selenium nanoparticles and lactic acid bacteria in reduction cadmium toxicity

Cadmium is a heavy metal, environmental pollutant and toxic for organisms. Lactic acid bacteria (LAB) and nanoparticles represent useful tools to remove heavy metals from different environments. The main goal of our study was to develop a novel experimental design for cadmium (Cd) disposal using L. casei or L. fermentum and exogenous selenium nanoparticles. The experimental design was developed in two steps. In the first step, bio-synthesis, morphological and chemical characterization of selenium nanoparticles (SeNPs) produced by L. casei was performed. In the next step, L. casei and L. fermentum were used to evidence their binding ability toward Cd, highlighting the role of SeNPs against Cd-induced toxicity. Homogenous, spherical shape SeNPs and sharp size distribution with maximum 200 nm were obtained via reduction route, using L. casei and Na2SeO3. Addition of Cd to LAB culture medium strongly inhibits both bacteria growth. SeNPs, in contrast to sodium selenite, clearly demonstrates the protective effect against Cd toxicity, as evidenced by dynamic growth curves of both bacteria. A better stimulation of endogenous SeNPs production was noticed for L. fermentum compared to L. casei. The efficiency of Cd bioabsorption by LAB was in the range 43.78%-50.87%, the ratio of 1:2 LAB/SeNPs showing the best results for both bacteria. The synergic effect of biogenic SeNPs and LAB against Cd toxicity was demonstrated. The combination of FTIR (Fourier Transform Infrared), FT Raman (Fourier Transformed Raman) and ICPOES (Inductively Coupled Plasma Optical Emission Spectroscopy) techniques provides specific qualitative and quantitative information on the behavior of probiotic species with respect to SeNPs synthesis and Cd disposal. (C) 2021 Elsevier B.V. All rights reserved.