Simultaneous chromate reduction and azo dye decolourization by Lactobacillus paracase CL1107 isolated from deep sea sediment

Lactobacillus paracase CL1107 capable of removing toxic chromium (Cr(VI)) and Acid Black (ATT) azo dye simultaneously was isolated from deep sea sediment of the North Atlantic. CL1107 exhibited appreciable dye-Cr(VI) bioremoval ability in the pH range from 5 to 7, temperature 25-35 °C and NaCl 0-6% under aerobic conditions. The maximum removal values of Cr(VI) (95.8%) and dye (92.3%) were obtained in the media including only Cr(VI) or dye at initial concentration of 100 mg/L. In the experiments for the simultaneous treatment of both pollutants, the reduction of Cr(VI) and dye was 58.5% and 51.9%, respectively. The azo dye and Cr(VI) reductive activities in strain CL1107 were located in the cell free extract and cell debris, respectively. The mechanisms of azo dye and Cr(VI) reduction were found to be enzyme-mediated. In the treatment of saline tannery wastewater, decolourization of about 76% and 63% Cr(VI) reduction of were achieved. Furthermore, Azo dyes, Cr(VI) and wastewater showed reduced toxicity toward Artemia salina after treatment. These results demonstrate the potential of CL1107 in bioremediation of dye or/and Cr(VI) contamination in salt environments.