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Efforts to optimize bioethanol production were made by modifying culture condition of the yeasts used. Two commercial yeast (New Aule alcohol yeast and New Aule baker's instant dry yeast) were grown in sugarcane molasses under different condition with and without aeration in order to compare the productivity of both yeast. The fermentation processes were carried out in batch condition for 72 hours incubation time. Aeration rate of 0.3 vvm were provided for four hours at the early stage of the aerated cultures. The level of ethanol produced by New Aule Alcohol Yeast was 74.8 g/L with ethanol productivity of 2.078 g/L/h and yield (Yp/s) was at 0.378 g/g. Aeration of 0.3 vvm did not affect the level of ethanol produced, yielded 0.338 gram of ethanol per gram of substrate used. Interestingly, the result showed that the New Aule baker's instant dry yeast produced higher ethanol compare to that of its alcohol yeast. Without aeration, New Aule baker's instant dry yeast produced 102.854 g/L. Meanwhile, the aerated culture of this yeast increase the ethanol production to the level of 120.917 g/L with productivity 3.359 g/L/h and ethanol yield 0.669 g/g, indicating the differences in oxygen sensitivity of both commercial yeast. [ABSTRACT FROM AUTHOR]