Reducing capacity and enzyme activity of chromate reductase in a ChrT-engineered strain

In order to remediate the metal-contaminated soil and water ecosystems with microorganisms, an engineered strain, which contained the chromate reductase ChrT gene from Serratia sp. S2, was studied in detail for its Cr (VI) reduction efficiency, optimal culture condition and chromate reductase activity. Results demonstrated that the engineered strain had a high Cr (VI) reduction rate of up to 40% at a concentration of 50 mg/l after being cultured for 48 h. Additionally, the optimal culture conditions were pH 7.0 and 37°C. Furthermore, the carbon sources and metal cations exhibited significant effects on the Cr (VI) reduction rate of the engineered bacterium. Sodium lactate, sodium acetate, Cu²⁺, Co²⁺ and Pb²⁺ were positively correlated with the reduction rate. Chromate reductase was soluble and presented in the cytoplasm. Furthermore, the enzymatic activity with nicotinamide adenine dinucleotide phosphate, which was as an electron donor, reached 14.83 U/mg.