Potential use of Serratia marcescens CCMA 1010 in biossorption of toxic metals

Abstract

Microorganisms are important biotechnologies tools for decontaminations of wastes with heavy metals, because they present high efficiency and low cost. Among the process of treatment have the strategies of bioaugmentation utilizing the microbial biomass with biossorbent of heavy metals. The present study had objectives of identify among bacterias isolated of wastewater of coffee process those resistant at high concentrations of Pb 2+ , Cd 2+ and Zn 2+ , since the impact of these metals in physiology until the expression of resistance genes, in order to infer about the capacity of removal these metals in multi-contaminated environments. S. marcescens CCMA 1010 stood out by growth in until 4.0 mM of Pb 2+ , showing growth rate and generation time similar the control (without lead). However, the biological activity decreased in first 180 minutes of Pb 2+ exposition stabilizing after this time. Only zntR gene was detected inferring with exist a regulation mechanism of Zn, Cd and Pb presence in side of cell. In experiments of Pb 2+ removal in water was detected 100% of removal of Pb 2+ . However, in culture medium LB was observed low efficiency of metal ion removal (30%), utilizing the biomass active or inactive. The zntR gene don’t presented the high expression in the lead presence, thus suggesting, with the metal don’t was absorbed by bacterial cell. S. marcescens CCMA 1010 showed resistant at the Zn 2+ >Pb 2+ >Cd 2+ . The major removal rate of Pb 2+ (31.8%) and Cd 2+ (32.8%) was observed in pH 5.0 and initial concentration of 590 mg L -1 for the Pb 2+ and 470 mg L -1 for the Cd 2+ . The presence of metals reflected in variation of amine group, carboxyl, hydroxyl group and ligation of oxygen and nitrogen, thus suggesting, adsorption mechanisms of heavy metals in superficies of wall cell. The biomass of S. marcescens CCMA 1010 showed potential use in systems of treatment of wastewater contaminated of toxic metals beyond low nutritional exigency for biomass production.