Exponential feeding strategy of high-density cultivation of a salt-tolerant aroma-producing yeast Zygosaccharomyces rouxii in stirred fermenter

• The exponential feeding method was first used at the high density culture of Z. rouxii.
• The maximum cell dry weight was 72.86 g/L at the optimal special growth rate 0.5 h−1.
• This strategy avoid the accumulation of ethanol.
• The biomass concentration of Z. rouxii was the highest so far.

Salt-tolerant yeast Zygosaccharomyces rouxii is a key strain to produce flavor in soy sauce brewing. The aim of this research was to establish the optimal feeding strategy and parameter for high-density culture of Z. rouxii. An exponential feeding strategy was applied where the specific growth rate was fixed by limitation of the fed carbon source. The set point of specific growth rate of exponential feeding for fed-batch culture was chosen to be 0.03–0.07 h−1. The optimal set point of specific growth rate (μset) of exponential feeding started after glucose depletion for fed-batch culture was found to be 0.05 h−1. Furthermore, a relatively high-dense biomass (72.86 g/L dry cell weight) was obtained in the culture of exponential feeding started after glucose was exhausted with μset = 0.05 h−1. Less than the level of Saccharomyces cerevisiae and Pichia pastoris, however the biomass concentration was much higher than data from other research about Z. rouxii culture.