Aeration strategy: a need for very high ethanol performance in Saccharomyces cerevisiae fed-batch process.
In order to identify an optimal aeration strategy for intensifying bio-fuel ethanol production in fermentation processes where growth and production have to be managed simultaneously, we quantified the effect of aeration conditions--oxygen limited vs non limited culture (micro-aerobic vs aerobic culture)--on the dynamic behaviour of Saccharomyces cerevisiae cultivated in very high ethanol performance fed-batch cultures. Fermentation parameters and kinetics were established within a range of ethanol concentrations (up to 147 g l(-1)), which very few studies have addressed. Higher ethanol titres (147 vs 131 g l(-1) in 45 h) and average productivity (3.3 vs 2.6 g l(-1) h(-1)) were obtained in cultures without oxygen limitation. Compared to micro-aerobic culture, full aeration led to a 23% increase in the viable cell mass as a result of the concomitant increase in growth rate and yield, with lower ethanol inhibition. The second beneficial effect of aeration was better management of by-product production, with production of glycerol, the main by-product, being strongly reduced from 12 to 4 g l(-1). We demonstrate that aeration strategy is as much a determining factor as vitamin feeding (Alfenore et al. 2002) in very high ethanol performance (147 g l(-1) in 45 h) in order to achieve a highly competitive dynamic process.
Alfenore
S
S
Biotechnology and Bioprocess Laboratory, UMR-CNRS 5504, UMR-INRA 792, Institut National des Sciences Appliquées, Département de Génie Biochimique et Alimentaire, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France.
Cameleyre
X
X
Benbadis
L
L
Bideaux
C
C
Uribelarrea
J-L
JL
Goma
G
G
Molina-Jouve
C
C
Guillouet
S E
SE
D000332:Aerobiosis; D000388:Air; D018533:Biomass; D019149:Bioreactors; D003470:Culture Media; D000431:Ethanol / Q000032:analysis / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D007218:Industrial Microbiology / Q000379:methods; D007700:Kinetics; D010101:Oxygen Consumption; D012441:Saccharomyces cerevisiae / Q000254:growth & development* / Q000378:metabolism*; D013997:Time Factors; D014815:Vitamins / Q000494:pharmacology
D003470:Culture Media; D014815:Vitamins; D000431:Ethanol; D005947:Glucose; D005990:Glycerol