OF HEAVY METALS

Abstract

Heavy metals cause various health hazards. Using lactic acid bacteria (LAB), we tested the reduction of heavy metals e.g. chromium (Cr), lead (Pb) and copper (Cu). The metals levels sorption were tested in two bacterial strains (Lactobacillus plantarum and Lactobacillus rhamnosus) using atomic absorption spectrophotometery Flame Atomic Absorption Spectrometry (FAAS) by AA-7000 Shimadzu, the cell turbidity was (1×10 cells/ml). The results showed decreased in all metals levels (Pb, Cu and Cr ) in MRS broth. The Cr concentrations of the media in the pre-Lactic acid bacteria treatment s (25.39) mg/ml at 100 mg/ml concentration were significantly (p < 0.05). Lower than after-Cr treatment (18.57, 4.86) mg/ml by L. plantarum and L. rhamnosus respectively. The lead also decline at 100 mg/ml concentration from (28.66) mg/ml in control to (17.99 and 3.62) mg/ml by L. plantarum and L. rhamnosus respectively. The results of the copper reducing experiments were combined and the most promising strain, L. rhamnosus, which had the highest copper reducing capacity at 100 mg/ml of Cu concentration., the value reached to (7.39 mg/ml) compared with control (11.03 mg/ml). In order to optimize the best bio remediated bacterial strain Lactic acid bacteria were cultured in specific medium (MRS) at different incubation period (12 to 96)hrs, pH (3.0 to 7.0), and temperature (25 to 37 °C) ,and with or without oxygen. It was observed that maximum reduction at 12 h of incubation period, pH 3.0, and temperature 25 °C , in presence of oxygen. LAB specially L. rhamnosus bio sorption may aid the detoxification of people exposed to heavy metals.