Effects of light wavelength and intensity on the production of ethanol bySaccharomyces cerevisiaein batch cultures

Abstract

AbstractBACKGROUND:Photoreceptors have been identified inSaccharomyces cerevisae, however, the influence of light on the performance of ethanol fermentation ofS. cerevisiaeis not yet clear. The aims of this study are to elucidate the influence of light wavelength and intensity on the growth and ethanol production ofS. cerevisiaeand to describe a novel two‐stage LED light process to optimize ethanol fermentation.RESULTS:Experimental results indicated that maximum biomass concentration Xmaxof the batch under red LED light increased monotonically with light intensity, and the optimal specific product yield Yp/xwas 13.2 g g−1at 600 lux. Maximum ethanol concentration Pmaxof the batch under blue LED light increased monotonically with light intensity, and the optimal Yp/xwas 18.4 g g−1at 900 lux. A novel two‐stage LED light process achieved maximum Pmax, of 98.7 g dm−3resulting in 36% improvement compared with that of the batch in the dark.CONCLUSION:The light wavelength and its intensity significantly affected cell growth and ethanol formation ofS. cerevisiae. Red LED light (630 nm) stimulated cell growth but slightly inhibited ethanol formation. In contrast, blue LED light (470 nm) significantly inhibited cell growth but stimulated ethanol formation. A novel two‐stage LED light process has been successfully demonstrated to optimize ethanol fermentation ofS. cerevisiae. Copyright © 2009 Society of Chemical Industry