Process Biotechnology
Electronic Journal of Biotechnology ISSN: 0717-3458 Vol. 14 No. 1, Issue of January 15, 2011
© 2011 by Pontificia Universidad Católica de Valparaíso -- Chile Received July 15, 2010 / Accepted October 22, 2010
DOI: 10.2225/vol14-issue1-fulltext-2 How to reference this article

Ethanol production from sweet sorghum juice under very high gravity conditions: Batch, repeated-batch and scale up fermentation

Lakkana Laopaiboon*1,2 · Sunan Nuanpeng3 · Penjit Srinophakun4 · Preekamol Klanrit1 · Prasit Jaisil5 · Pattana Laopaiboon1

1Department of Biotechnology, Faculty of Technology, Khon Kaen University, Khon Kaen 40002 Thailand
2Fermentation Research Center for Value Added Agricultural Products, Khon Kaen University, Khon Kaen 40002 Thailand
3Graduate School, Khon Kaen University, Khon Kaen 40002 Thailand
4Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok, Thailand
5Department of Plant Science and Agricultural Resources, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand

*Corresponding author:

Financial support: Thailand Research Fund (TRF) and Commission on Higher Education, Thailand, Grant No. MRG4980199.

Keywords: batch, ethanol fermentation, repeated-batch, scale up, sweet sorghum, VHG.

Abstract   Full Text

Batch ethanol fermentations from sweet sorghum juice by Saccharomyces cerevisiae NP 01 were carried out in a 500 ml air-locked Erlenmeyer flask under very high gravity (VHG) and static conditions. The maximum ethanol production efficiency was obtained when 9 g l-1 of yeast extract was supplemented to the juice. The ethanol concentration (P), productivity (Qp) and yield (Yp/s) were 120.24 ± 1.35 g l-1, 3.01 ± 0.08 g l-1 h-1 and 0.49 ± 0.01, respectively. Scale up ethanol fermentation in a 5-litre bioreactor at an agitation rate of 100 rev min-1 revealed that P, Qp and Yp/s were 139.51 ± 0.11 g l-1, 3.49 ± 0.00 g l-1 h-1 and 0.49 ± 0.01, respectively, whereas lower P (119.53 ± 0.20 g l-1) and Qp (2.13 ± 0.01 g l-1 h-1) were obtained in a 50-litre bioreactor. In the repeated-batch fermentation in the 5-litre bioreactor with fill and drain volume of 50% of the working volume, lower P and Qp were observed in the subsequent batches. P in batch 2 to 8 ranged from 103.37 ± 0.28 to 109.53 ± 1.06 g l-1.

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