EVALUATION OF ENTEROCOCCUS DURANS E1T1 ISOLATED FROM INFANT FECES AS A PROMISING PROBIOTIC FOR CADMIUM DETOXIFICATION

Abstract

The purpose of the current study was to evaluate the ability of some metal-resistant lactic acid bacteria (LAB) to remove cadmium in order to highlight the importance of probiotic LAB in the detoxification of these pollutants at the level of the digestive tract or in fermented foods. Infant feces samples were used to isolate Cd-resistant LAB, they were screened using the spread plate technique on agar media after being supplemented with cadmium at an initial concentration of 50 mg.L-1. In this research, out of 106 isolates tested for Cd-resistance, 11 isolates were selected based on their high capacity to grow in presence of cadmium. After which they were tested for their ability to resist different heavy metals and for probiotic properties. The study was completed using the isolate E1T1 identified as Enterococcus durans based on 16S rRNA gene sequence, which showed the highest cadmium (MIC 600 mg.L-1) and other heavy metals resistance capacity and better probiotic properties. The selected isolate presented strong adhesion ability to epithelial cells, good antibacterial activity, and was non-hemolytic. Furthermore, it had excellent cadmium removal efficiencies, with rates of 65.94% and 28.78% after 96 hours in living and dead cells, respectively. E. durans E1T1 had also high cadmium accumulation efficiencies, with an estimated value of 11.47 mg Cd.g-1 of cells (wet weight). According to the findings from the study, the Cd-resistant E. durans E1T1 may be employed as a promising probiotic isolate for removing cadmium.