Incorporation of copper ions by yeast Kluyveromyces marxianus during cultivation on whey

The production of Kluyveromyces marxianus biomass enriched with copper ions were studied. For that reason the growth of Kluyveromyces marxianus in whey with different concentrations of copper ions in batch process under semiaerobic and aerobic conditions were examined. The kinetics of copper ions accumulation in yeast cells, under the same conditions, as well as the reduction of chemical oxygen demand (COD) during yeast growth in aerobic condition, were monitored, as well. The concentration of copper ions in media up to 4 mg l(-1) did not affect the yeast growth, whereas at a higher concentration, a marked decrease in the rate of yeast growth, ethanol production and lactose consumption occurred. In semiaerobic conditions, the maximum uptake of 0.35 mg Cu g(-1) d.m. was obtained, while in aerobic conditions a lower uptake of 0.26 mg Cu g(-1) d.m. and COD reduction of 85% were achieved. COD reduction was independent of the copper addition or uptake.