Human Metallothionein Enhanced Tolerance and Biosorption of Cadmium when Expressed in <i>Saccharomyces cerevisiae</i>

Abstract

The recombinant Saccharomyces cerevisiae expressing human hepatic metallothionein (MT) was constructed for biosorption of cadmium (II). The gene sequence of mt was modified for codon preference of S. cerevisiae and synthesized using chemical method. The maximal biosorption capability of cadmium compounds Cd2+ of the recombinant increased more than 25.8% compared with the control. For MT-expressed recombinant strains, a rapid adsorption occurred within the first 30 min with a significant level of Cd2+ (55.75mg/g). For comparison, S. cerevisiae cells reach its maximal Cd2+ adsorption capacity (45.02 mg/g) until 2h. Furthermore, recombinant strain were able to withstand the toxicity of Cd2+ and grow. The results indicated that recombinant should be useful in enhancement the tolerance and biosorption of cadmium in practice.

Gradual Accumulation of Heavy Metals in an Industrial Wheat Crop from Uranium Mine Soil and the Potential Use of the Herbage

“…Baker's yeast (Saccharomyces cerevisiae) as the preferred ethanologenic organism experienced 5% and EC50 growth inhibition in solution at 0.11 and 1.12 mg·L −1 , respectively, in Cd; 55 and 96 mg·L −1 , respectively, in Mn; 59 and 117 mg·L −1 , respectively, in Ni; and 65 and 163 mg·L −1 , respectively, in Zn during 12 h of incubation [57]. The yeast exposed to 10 mg·L −1 Cd was temporarily inhibited to regain an almost normal growth rate [120] apparently owing to its biosorption capacity in the order of 45 mg Cd 2+ per gram of biomass within 2 h [121]. Exposure to Cu reduced the viability of the yeast cells to 88% at 0.32 mg·L −1 within 1 h and to 11% at 2.54 mg·L −1 within 5 min [60].…”