Enhanced Pb~(2+) biosorption by recombinant Saccharomyces cerevisiae expressing human metallothionein

摘要

Recombinant Saccharomyces cerevisiae expressing human hepatic metallothionein (SC-mt) was constructed for biosorption of lead(II). The gene sequence of mt was modified for codon preference of S. cerevisiae (SC) and synthesized using a chemical method. The influences of different experimental parameters such as solution pH, initial concentration, contact time, and temperature on adsorption were investigated. SC and SC-mt showed the highest Pb(H) sorption capacity at initial pH of 5.0 and contact time of 30 min. Adsorption on SC-mt was more favorable than on SC; in addition, the saturated monolayer sorption capacity increased from 80.00 to 181.82 mg/g at 298 K. Adsorption kinetics was better described by a pseudo-second-order model, and the adsorption process could be well described by the Langmuir isotherm. Thermodynamic parameters of SC-mt, namely ΔG°(298 K), ΔH°, and ΔS°, were determined to be -17.91 and 12.13 kJ mol~(-1), and 100.81 J mol~(-10 K~(-1) respectively, demonstrating that the sorption process of SC-mt towards Pb(II) was feasible, spontaneous, and endothermic in nature. The results indicate that the recombinant S. cerevisiae SC-mt should be useful for enhancement of the effectiveness of lead biosorption in practice.