Journal of Applied Sciences1812-56541812-5662Asian Network for Scientific Information10.3923/jas.2009.3126.3130EmilyL.W.T. NandongJ. SamyudiaY. 122009917The impact of aeration rate and stirrer speed on micro-aerobic fermentation is studied at laboratory scale. Result suggests that with Bakers yeast, an increase in aeration rates from very low value can improve bioethanol productivity and yield because it can enhance cell viability. At constant stirrer speed of 150 rpm, the increase in aeration rate from 1 to 1.5 LPM leads to proportional increase in peak Oxygen Uptake Rate (OUR) from 600 to 1000 mM L-1 h. This increase coincides with the increase in yield by 7.5%. Interestingly at constant aeration rate of 1.5 LPM, an increase in stirrer speed from 150 to 250 rpm leads to decrease in peak OUR from 1000 to 457 mM L-1 h but increase in yield by 64%. In conclusion, both stirrer speed and aeration rate are important factors which have complex impacts on hydrodynamics and microbial metabolism, which in turn affect productivity and yield. Further study using CFD modeling and simulation method is required to gain better insights into how aeration rate and stirrer speed affect metabolism via the mixing mechanisms in a bioreactor.]]>Alexandre, H., I. Rousseaux and C. Charpentier,1994Saccharomyces cerevisiae.]]>20173183Alexandre, H., I. Rousseaux and C. Charpentier,1994Saccharomyces cerevisiae and Kloeckera apiculata.]]>1241722Anderasen, A.A. and T.J.B. Stier,1953Saccharomyces cerevisiae. I. Ergosterol requirement for growth in a defined medium.]]>412326Bideaux, C., S. Alfenore, X. Cameleyre, C. Molina-Jouve, J.L. Uribelarrea and S.E. Guillouet,2006Saccharomyces cerevisiae, using a metabolic model as a prediction tool.]]>7221342140Casey, G.P. and W.M. Ingledew,198613219280Chabes, A., V. Domkin and G. Larsson,20009724742479Chi, Z. and N. Arneborg,1999Saccharomyces cerevisiae.]]>8610471052Cot, M., M. Loret, J. Francois and L. Benbadis,2007Saccharomyces cerevisiae in aerated fed-batch fermentation for high level production of bioethanol.]]>72232Ghareib, M., K.A. Youssef and A.A. Khalil,1988Saccharomyces cerevisiae and its relationship to lipid content and composition.]]>33447452Hoppe, G.K. and G.S. Hansford,1984Saccharomyces cerevisiae.]]>6681686Koukou, A.I., D. Tsoukatos and C. Drainas,1990Schizosaccharomyces pombe membranes.]]>13612711277Nagy, M., F. Lacroute and D. Thomas,19928989668970Snoek, I.S.I. and H. Steensma,2007Saccharomyces cerevisiae.]]>24110Sonnleitner, B., S. Rothen and H. Kuriyama,199713813Wang, Z.X., J. Zhuge, H. Fang and B.A. Prior,200119201223Zaldivar, J., J. Nielsen and L. Olsson,2001561734