Effect of the dissolved oxygen on the bioproduction of glycerol and ethanol by Hansenula anomala growing under salt stress conditions.
The effect of the dissolved oxygen on glycerol and ethanol productions by an osmotolerant yeast Hansenula anomala was examined during growth in media at low water activity resulting from the addition of 2M NaCl in the culture medium. High stirring rate, high culture medium aeration, as well as high mass transfer surface inhibited both glycerol and ethanol biosynthesis. In absence of oxygen, yeast used acetaldehyde as a hydrogen acceptor, leading to the stimulation of ethanol biosynthesis and accounting for the low biomass and glycerol production; the experimental ratio ethanol on glycerol produced was 5.1 when the available oxygen was lowered (low stirring rate, 500rpm) and increased to 10.2 in absence of aeration. Extracellular glycerol production was therefore optimal for a moderate stirring (1000rpm) and aeration (1.4vvm) rates. These optimal conditions resulted in an experimental ratio ethanol on glycerol produced of 4.1, namely close to the theoretical value of 4, illustrating the osmodependent channelling of carbon towards polyols production.
Equipe Chimie et Ingénierie des Procédés, Université de Rennes 1/ENSCR, UMR CNRS 6226 Sciences Chimiques de Rennes, ENSCR, Campus de Beaulieu, Avenue du Général Leclerc, 35700 Rennes, France.
H
H
Djelal
F
F
Larher
G
G
Martin
A
A
Amrane
D018533:Biomass; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005947:Glucose / Q000737:chemistry / Q000235:genetics; D005990:Glycerol / Q000378:metabolism*; D008956:Models, Chemical; D009994:Osmolar Concentration; D010100:Oxygen / Q000378:metabolism* / Q000494:pharmacology; D010843:Pichia / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry / Q000378:metabolism; D012965:Sodium Chloride / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D012995:Solubility; D013997:Time Factors
D003470:Culture Media; D000644:Quaternary Ammonium Compounds; D000431:Ethanol; D012965:Sodium Chloride; D005947:Glucose; D005990:Glycerol; D010100:Oxygen