Novel Probiotic Lactic Acid Bacteria with In Vitro Bioremediation Potential of Toxic Lead and Cadmium

In this study, newly isolated lactic acid bacteria (LAB) were screened for the potential bioremediation capacity against toxic lead (Pb, II) and cadmium (Cd, II) with their bioaccessibility and survivability. Five strains were selected from eighteen previously isolated probiotic LAB strains based on heavy metal-resistant potentiality through in vitro disc-diffusion assay. These five strains were evaluated in vitro to explore the Pb and Cd binding and removal efficiencies using Flame Atomic Absorption Spectrophotometry. At the same time, their bioaccessibility and survivability were assessed in a dynamic in vitro gastrointestinal digestion model. The results revealed that all the tested strains were shown to have a high magnitude of minimum inhibitory concentration values ranging from 500 to 2000 mg/L with 5 to 25 mm growth inhibition zones. The results also demonstrated a significant (P < 0.05) removal of Pb and Cd among five tested LAB strains. Lactobacillus delbrueckii subsp. bulgaricus LDMB02 showed the highest removal rates of Pb and Cd. It was also revealed that these strains significantly reduced Pb and Cd bioaccessibility from 42 to 50% and 40 to 58%, respectively. Moreover, these strains were shown to have significant survivability against Pb and Cd, ranging from 80.1 to 85.4% and 81.5 to 87.5%, respectively. This study recommends the immense potential exploit of LAB as a probiotic to protect human health from the adverse effects of Pb and Cd toxicity.