Open AccessFormation of ethyl acetate by K luyveromyces marxianus on whey: Influence of aeration and inhibition of yeast growth by ethyl acetate
Author(s) -
Urit Thanet,
Manthey Rene,
Bley Thomas,
Löser Christian
Publication year - 2013
Publication title -
engineering in life sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.547
H-Index - 57
eISSN - 1618-2863
pISSN - 1618-0240
DOI - 10.1002/elsc.201200077
Subject(s) - kluyveromyces marxianus , aeration , ethyl acetate , bioreactor , chemistry , yeast , chromatography , fermentation , kluyveromyces , acetic acid , food science , biochemistry , organic chemistry , saccharomyces cerevisiae
The ability of the yeast K luyveromyces marxianus to convert lactose into ethyl acetate offers good opportunities for the economical reuse of whey. The formation of ethyl acetate as a bulk product depends on aerobic conditions. Aeration of the bioreactor results in discharge of the volatile ester with the exhaust gas that allows its process‐integrated recovery. The influence of aeration (varied from 10 to 50 L/h) was investigated during batch cultivation of K . marxianus DSM 5422 in 0.6 L whey‐borne medium using a stirred reactor. With lower aeration rates, the ester accumulated in the bioreactor and reached higher concentrations in the culture medium and the off gas. A high ester concentration in the gas phase is considered beneficial for ester recovery from the gas, while a high ester concentration in the medium inhibited yeast growth and slowed down the process. To further investigate this effect, the inhibition of growth by ethyl acetate was studied in a sealed cultivation system. Here, increasing ester concentrations caused a nearly linear decrease of the growth rate with complete inhibition at concentrations greater than 17 g/L ethyl acetate. Both the cultivation process and the growth rate depending on ethyl acetate were described by mathematical models. The simulated processes agreed well with the measured data.