Microelements is a chemical element required in small amounts to sustain the life of microorganisms. Microelements needed by microorganism in the metabolism as a cofactor of various enzymes that exist. Effect of growth conditions and fermentation of Saccharomyces cerevisiae which has been supplemented with iron, selenium, and magnesium were studied. Growth of S. cerevisiae was carried out at three different temperatures (27°C, 30°C, dan 37°C) and pH (4, 5, dan 6) at growth media barley juice and brown rice juice. Fermentation of S. cerevisiae was performed on two different conditions, anaerobic and semiaerobic. The results showed that the optimum growth conditions is at temperature of 27°C and pH 5 with semiaerobic fermentation conditions. Optimal fermentation conditions were determined using multiple test parameters, namely TPC, the amount of biomass, and the amount of ethanol produced.