In vitro Assessment of Chromium, Lead, Cadmium and Nickel Tolerance of B. clausii, a Prospective Probiotic Microorganism for in vivo Bioremediation

摘要

Researches have demonstrated the ability of probiotic microorganisms to prevent and treat ailments especially those associated with the gastrointestinal tract. Probiotics like Lactobacillus spp. have also displayed the property of bioremediation of heavy metals under in vitro as well as in vivo conditions. The aim of this study was to assess the effects of chromium, lead, cadmium and nickel stress on the properties of B. clausii, a probiotic species of genus Bacillus. The minimum inhibitory concentration (MIC) of the organism under test was determined for Cr (VI), Pb (II), Cd (II) and Ni (II), followed by assessment of morphological and biochemical properties of the B. clausii, antibiotic sensitivity and probiotic efficacy by acid and bile toleranceassays. B. clausii exhibited exceptionally high MICs for the tested heavy metals. The organism did not exhibit any change in its morphological and biochemical characteristics after exposure to heavy metal stress. This stress also did not affect the testorganism’s probiotic behaviour as assessed by acid and bile tolerance assays where it showed maximum growth at 3 hrs. for pH 3 and 0.3% bile concentration, respectively. However, after exposure to the four heavy metals, B. clausii showed a tremendous increase in its antibiotic sensitivity. The above study has indicated the capacity for B. clausii to survive in and tolerate high levels of Cr (VI), Pb (II), Cd (II) and Ni (II) while showing no change in its characteristics. Therefore, B. clausii appearsto be an ideal candidate for potential bioremediation of Cr (VI), Pb (II) Cd (II) with Pb(II), Cd (II) and Ni (II), in vivo.