Efficacy of indigenous probiotic Lactobacillus strains to reduce cadmium bioaccessibility - An in vitro digestion model

Abstract

The toxic heavy metal cadmium (Cd) appears as one of the major global threats to human and animal health. Human being and aquatic life are exposed to Cd by breathing, eating, or drinking when industrial effluents released into environment. The study was aimed to identify cadmium-binding Lactobacillus strain to reduce its bioaccessibility in in vitro digestion model. In this context, forty-eight lactobacilli strains isolated and characterized from fermented dairy products and human origin were screened for their Cd biosorption potential using Flame Atomic Absorption Spectroscopy (FAAS). The present study revealed that Cd biosorption potential of 48 lactobacilli strains ranged from 1.0832 ± 0.012 to 3.562 ± 0.03 mg Cd g⁻¹ of cells from initial 10 mg L⁻¹ cadmium chloride (CdCl₂) aqueous solution. Lactobacillus plantarum strain HD 48 demonstrated highest biosorption of 3.562 ± 0.03 mg Cd g⁻¹ of cells. Lactobacilli-Cd complex stability indicated its strong stability as even after three washes with Milli-Q water metal desorption was nonsignificant (p < 0.05) and further studies to delineate the influence of Cd (100 mg L⁻¹ CdCl₂) on their growth. Moreover, these strains were able to reduce Cd bioaccessibility in the in vitro digestion model in the range of 24.71 to 41.62 %. Transmission electron microscopy (TEM) investigations on Cd bioadsorption also revealed its surface associated bioadsorption phenomenon. These findings depicted that probiotic strain L. plantarum HD 48 was found to be endowed with remarkable Cd biosorption ability as well as reduction in its bioaccessibility. These results suggest that probiotic strain L. plantarum HD 48 has immense potential to sequester Cd from aqueous solution which could be further explored as a potent source to diminish body Cd burden.

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