Alternatively, some researchers inoculated their entire hybrid population in a very high-gravity fermentation and harvested cells for a next round of shuffling when the viability of the culture had considerably dropped, thereby enriching for the best adapted hybrids (Hou, 2010; Liu et al., 2011).
Adh1p and Adh2p were found to be located in the cytosol, were the main functional alcohol dehydrogenases under anaerobic conditions, and kept a high transcriptional level under very high gravity conditions [ 26, 30], which was in accordance with our results in this article.
However, the high sugar content of the very high gravity fermentation medium causes an increase in the osmotic pressure, which has a pessimistic effect on yeast cells, and the fermentations are rarely fast and complete.
The three new superior strains exhibited significantly increased tolerance to various inhibitors in spruce hydrolysate, faster growth rate in glucose medium and a faster glucose consumption rate and higher ethanol accumulation capacity in very high gravity fermentations.
The aim of this study was to optimize the aeration rate and time for high levels of ethanol production under very high gravity (VHG) fermentation by Saccharomyces cerevisiae NP 01 using a factorial design based on response surface methodology (RS M.
Very high gravity (VHG) fermentation technology was subsequently carried out to achieve a high ethanol concentration at 86.4 g/L.
While it was not possible to evaluate the positive benefit of this deletion with the set-up used for the fermentations (expected concentrations of ethanol lower than 3% v/v), APJ1 can be considered as a good candidate for integration of expression cassettes in strains to be used during very high gravity fermentations.
Nitrogen sources, the critical media component, were optimized to enhance ethanol production by Saccharomyces cerevisiae in very high gravity (VHG) fermentation of corn starch (340 g/l).
An in-depth understanding of the mechanism of yeast stress tolerance contributes to breeding more robust strains for ethanol production, especially under very high gravity conditions.
