Brettanomyces bruxellensis: effect of oxygen on growth and acetic acid production

Abstract

The influence of the oxygen supply on the growth, acetic acid and ethanol production by Brettanomyces bruxellensis in a glucose medium was investigated with different air flow rates in the range 0-300 l h(-1 ) x (0-0.5 vvm). This study shows that growth of this yeast is stimulated by moderate aeration. The optimal oxygen supply for cellular synthesis was an oxygen transfer rate (OTR) of 43 mg O(2) l(-1) x h(-1). In this case, there was an air flow rate of 60 l h(-1) (0.1 vvm). Above this value, the maximum biomass concentration decreased. Ethanol and acetic acid production was also dependent on the level of aeration: the higher the oxygen supply, the greater the acetic acid production and the lower the ethanol production. At the highest aeration rates, we observed a strong inhibition of the ethanol yield. Over 180 l h(-1) x (0.3 vvm, OTR =105 mg O(2) l(-1) x h(-1)), glucose consumption was inhibited and a high concentration of acetic acid (6.0 g x l(-1)) was produced. The ratio of "ethanol + acetic acid" produced per mole of consumed glucose using carbon balance calculations was analyzed. It was shown that this ratio remained constant in all cases. This makes it possible to establish a stoichiometric equation between oxygen supply and metabolite production.

Modeling of yeast Brettanomyces bruxellensis growth at different acetic acid concentrations under aerobic and anaerobic conditions

“…This yeast has low nutritional requirements [8], and is well known to be sensitive to oxygen availability [9,10]. Custer (1940) (cited in [4]) found that resting cells of Brettanomyces claussenii under aerobic conditions fermented glucose at a higher rate than in the absence of oxygen.…”

Conventional and Non-Conventional Yeasts in Beer Production

“…On the contrary, when some non-conventional yeasts are employed (i.e., Torulaspora delbrueckii and Brettanomyces spp. ), low level of oxygen is necessary to support fermentation [26,27]. In the case of co-cultivation of Saccharomyces and nonconventional yeasts, this dependence on oxygen may play a positive role in controlling the growth of the latter, thereby ensuring successful completion of fermentation by the former.…”

The Microbiology of Malting and Brewing

“…These yeasts spoil beer through the production of the highly volatile phenolic compounds 4-ethylguaiacol and 4-ethylphenol, lending the aroma of bandages, sweat, and smoke. A number of other metabolites, including copious acetate production in the presence of oxygen (234), result in a wide range of off-flavors produced by these yeasts. In spite of its reputation, Brettanomyces is a desired component of certain beers, particularly Belgian lambic (see below) and fruit beers, in which its beta-glycosidase activity enhances fruit aroma (235).…”