Biosorption and bioaccumulation of nickel by probiotic lactic acid bacteria isolated from human feces

Nickel is a heavy metal that has a variety of negative impacts on living organisms and causes different health disorders. Probiotic bacteria have been recently utilized for nickel detoxification through bioremediation strategies. We inspected that the role of probiotic lactic acid bacteria in reducing nickel toxicity has been investigated using two biological methods, including biosorption and bioaccumulation. Seventeen strains of nickel-resistant probiotic lactic acid bacteria isolated from the human microbiome were selected out of 88 strains by three different screening stages comprising disc diffusion, MIC, and biosorption/bioaccumulation tests culminated in four of the most powerful strains in reducing nickel from their culture medium. They were L. brevis 205, L. mocusae 226, L. casei 375, and B. infantis 1001 with the mean nickel biosorption rate of 82%, 66%, 70%, and 74%, respectively. The bioaccumulation test resulted in an approximate rate of accumulated nickel inside the strains cells. L. casei, L. brevis, and L. mocusae had the best rate of about 43% nickel accumulation, followed by B. infantis with a 42% bioaccumulation rate. This study supports that the theory of applying probiotic lactic acid bacteria to food and water detoxification could be a safe, bio-friendly alternative for gut remediation and in edible industries.