Investigation of the role of chromium reductase for Cr (VI) reduction by Pseudomonas species isolated from Cr (VI) contaminated effluent

This study observed the role of pH, chromium (VI) concentrations, temperatures and chromium reductases for of Cr (VI) reduction. Bacteria isolated from effluent were identified as Pseudomonas sp. by molecular analysis. Bacterial strain MAI4 showed significant reduction at pH 7 (84%), 100 μg Cr (VI)/ml (86%) and 35 °C (86%). Increase in time of incubation increased Cr (VI) reduction by P. entomophila MAI4 significantly and 120 h of incubation showed maximum reduction of Cr (VI). P. entomophila MAI4 also showed significant reduction of Cr (VI) (80%) in industrial waste water. Bacterial strain MAI4 reduced Cr (VI) into Cr (III) after 120 h which was detected as 70 ± 3 μg/ml in cell pellet and 30 ± 2 μg/ml in supernatant, respectively. Chromium reductase found in cell free extracts (CFE) reduced almost all Cr (VI) to Cr (III) compared to cell debris. Based on reduction under in vitro and in vivo conditions, Pseudomonas sp. MAI4 could be used as a bioremediator of Cr (VI) in contaminated effluents.