Fed-batch cultivation of baker's yeast followed by nitrogen or carbon starvation: effects on fermentative capacity and content of trehalose and glycogen.
An industrial strain of Saccharomyces cerevisiae (DGI 342) was cultivated in fed-batch cultivations at a specific growth rate of 0.2 h(-1). The yeast was then exposed to carbon or nitrogen starvation for up to 8 h, to study the effect of starvation on fermentative capacity and content of protein, trehalose and glycogen. Nitrogen starvation triggered the accumulation of trehalose and glycogen. After 8 h of starvation, the content of trehalose and glycogen was increased 4-fold and 2-fold, respectively. Carbon starvation resulted in a partial conversion of glycogen into trehalose. The trehalose content increased from 45 to 64 mg (g dry-weight)(-1), whereas the glycogen content in the same period was reduced from 55 to 5 mg (g dry-weight)(-1). Glycogen was consumed faster than trehalose during storage of the starved yeast for 1 month. Nitrogen starvation resulted in a decrease in the protein content of the yeast cells, and the fermentative capacity per gram dry-weight decreased by 40%. The protein content in the carbon-starved yeast increased as a result of starvation due to the fact that the content of glycogen was reduced. The fermentative capacity per gram dry-weight was, however, unaltered.
Centre for Process Biotechnology, BioCentrum-DTU, Technical University of Denmark, Building 223, 2800 Kgs. Lyngby, Denmark.
H
H
Jørgensen
L
L
Olsson
B
B
Rønnow
E A
EA
Palmqvist
D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D005285:Fermentation; D005656:Fungal Proteins / Q000032:analysis; D006003:Glycogen / Q000032:analysis / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000254:growth & development*; D014199:Trehalose / Q000032:analysis / Q000378:metabolism*
D005656:Fungal Proteins; D002244:Carbon; D006003:Glycogen; D014199:Trehalose; D009584:Nitrogen