An In Vitro Control Study to Test the Yeast Saccharomyces cerevisiae Strain BCA61 for Contaminated Soils Bioremediation.

Introduction The bioaccumulation and bioaugmentation of heavy metals has become a very serious environmental problem as it negatively affects microbial processes in agricultural soils and human health through the food chain. The estimated costs for the conventional soil remediation are very high, so within the more economic and ecofriendly technologies, bacteria, fungi and plants have been used since long time with extremely variable results. Aim of our study was to evaluate the ability of Saccharomyces cerevisiae BCA61 to uptake heavy metals using an in vitro study and to assess its applicability for environmental reclamation. Materials and Methods The uptake capacity of S. cerevisiae BCA61 was evaluated in Malt Extract Broth with 4 increasing concentrations, respectively of Ni (120; 150; 225 and 262 mg/300 mL of broth), Cd (3.6; 4.5; 6.75; 7.88 mg/300 mL), Cu (144; 180; 270 and 315 mg/300 mL) and As (12; 15; 22.5; 26 mg/300 mL) by performing 3 replicates for each concentration and one control constituted by the not fortified culture broth. The analyses were performed with Elan DRC-e Perkin Elmer ICP-MS. Results The S. cerevisiae strain has absorbed moderately Ni, Cu and As and to a greater extent the Cd (Fig. 1). In particular was calculated an uptake capacity respectively of 6-5.2-4.4-4.1% for Ni; 29-21.7-16-33.5% for Cd; 9.6-9.5-5.3-4.9% for Cu; 9.7-7.9-5.9-7% for As. The % uptake was calculated as average of the values obtained from the three independent replicates. Discussion S. cerevisiae is able to grow in the medium singularly fortified with Ni, Cd, Cu and As, showing a good ability to uptake the heavy metals. However, the yeast exposed to Cu shows a nonlinear uptake respect to Ni, Cd and As. So, it is probable that a toxic effect for the highest doses of Cu can interfere with cell growth, then lowering the uptake capacity (Peng et al. 2010).