Combined effects of molasses sucrose and reactive dye on the growth and dye bioaccumulation properties of Candida tropicalis

The combined effects of molasses sucrose and Remazol Blue or Remazol Black B reactive dye on the growth and dye bioaccumulation properties of adapted Candida tropicalis yeast was investigated in a batch system as a function of initial dye and sucrose concentrations. At a constant sucrose concentration, although the increase in initial dye concentration up to approximately 1000 mg l−1 increased the dye bioaccumulation capacity of yeast for both the dyes, all dye concentrations tested inhibited the growth of C. tropicalis. The cell and bioaccumulated dye concentrations and uptake yields increased with increasing sucrose concentration up to 15 g l−1 at a constant dye concentration for each of the dyes. In 10 g l−1 sucrose and about 1000 mg l−1 dye containing medium the dye adapted yeast was capable of accumulating of Remazol Black B and Remazol Blue dyes with a maximum uptake capacity of 167.5 and 163.3 mg dye per g of dry cells, respectively. The inhibition effect of dye anions on the specific growth rate of yeast was expressed by the non-competitive inhibition model (assuming the dye anions as the toxic inhibitory component) and model parameters were determined by graphical method.