Formation of ethyl acetate by Kluyveromyces marxianus on whey: Influence of aeration and inhibition of yeast growth by ethyl acetate. Issue 3 (3rd January 2013)

• Record Type: Journal Article
• Authors: Urit, Thanet; Manthey, Rene; Bley, Thomas; Löser, Christian
• Is Part Of: Engineering in life sciences. Volume 13:Issue 3(2013:May)
• Page Start: 247
• Page End: 260
• Publication Date: 2013-01-03
• Subjects: Bioengineering -- Periodicals; 660.605
• DOI: 10.1002/elsc.201200077
• Languages: English
• ISSNs: 1618-0240

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The ability of the yeast <italic>Kluyveromyces marxianus</italic> 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 <italic>K. marxianus</italic> 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.</p> </abstract>