Characteristics of Cd~(2+) Accumulation by A Yeast Strain Isolated from Mine Soil

With the development of mining, smelting, plating and so on, the s ur vival quality of human and other species are being threatened by more and more i ndustrial pollution. Cadmium is one of the most severe toxic metals. In recent y ears, researchers are seeking their way on bioremediation of Cd2+contamination, especially paying more attention to cadmium accumulation by microorganism. In o rder to get microbes with high capacity of cadmium accumulation and provide poss ible application in practice, A Yeast strain, designated as Y11, which could sur vive in medium with 2 000 mg·L-1of cadmium, was isolated from blende soil coll ected in Hebei province and the ability of cadmium absorption was determined by H2S fumigation in plates. The removal efficiency of Cd2+was highest, up to 95.6 %, under 6 g·L-1 lyophilized biomass of Y11 and 50 mg·L-1Cd2+conditions. T he lyophilized biomass could accumulate Cd2+more quickly than wet biomass thoug h their accumulation time course was similar. The bioadsorbed cadmium could be d esorbed under low pH, with desorption rate 75.4%～1.66%under pH 3.18～9.21, an d the desorbed biomass could re-adsorb Cd2+under high pH. Nearly 99%of the bi oadsorbed cadmium by Y11 distributed in cell wall and only 1%cadmium was found in cytoplasm, while 96.7%Cd2+was on the wall and 3.3%Cd2+was in cytoplasm in cadmium-induced incubated Y11 cells. Biosorption efficiency, cadmium capacity and uptake time of Y11 provided some datum for the industrial application. Cadmi um absorption and desorption in different pH suggested that sorption might be th e primary factor of cadmium uptakes by Y11 and Y11 might be a good bio-sorbent on biofilm for treating cadmium-containing industrial effluents and had an appl icable prospect in bioremediation of cadmium contamination in soil.