Acetaldehyde addition throughout the growth phase alleviates the phenotypic effect of zinc deficiency in Saccharomyces cerevisiae

Abstract

During experiments to determine the effects of exogenously added acetaldehyde on pure cultures of various yeast strains, we discovered that an early acetaldehyde perfusion during the growth phase allowed several yeasts to partially overcome the phenotypic effects of zinc depletion during alcoholic fermentation. We, therefore, performed genome-wide expression and proteomic analysis on an industrial Saccharomyces cerevisiae yeast strain (VL1) growing in zinc-replete or zinc-depleted conditions in the presence of perfused acetaldehyde to identify molecular markers of this effect. Zinc depletion severely affects ethanol production and therefore nicotinamide adenine dinucleotide (NAD) regeneration, although we observed partial compensation by the upregulation of the poorly efficient Fe-dependent Adh4p in our conditions. A coordinate metabolic response was indeed observed in response to the early acetaldehyde perfusion, and particularly of the lower part of glycolysis, leading to the cellular replenishment of NAD cofactor. These various findings suggest that acetaldehyde exchange between strains may inhibit the growth of some yeast strains while encouraging the growth of others. This phenomenon could be particularly important for understanding the ecology of colonization of complex fermentation media by S. cerevisiae after elimination of non-Saccharomyces yeasts.

Evaluation of the acetaldehyde production and degradation potential of 26 enological Saccharomyces and non-Saccharomyces yeast strains in a resting cell model system

“…SO 2 , the major wine preservative, strongly binds to acetaldehyde essentially removing it as electron acceptor from AF, and leading to increased acetaldehyde production by yeast as a result [25,26]. It is known that acetaldehyde production among wine yeast is strain specific [20,36] and several studies have suggested to survey yeast acetaldehyde production and to include this trait among yeast strain selection parameters [6,31]. However, no data quantifying acetaldehyde production among Saccharomyces and nonSaccharomyces wine yeast under comparable and easily reproducible conditions are available.…”

Zinc accumulation and utilization by wine yeasts

“…21 Very few publications are available on the infl uence of metal ions in grape must on yeast fermentation performance. [22][23][24][25] Commercial yeast food preparations based on a mixture of nutrients such as organic and inorganic nitrogen, fatty acids, sterols, vitamins and mineral salts (including zinc) are usually added during yeast rehydration and propagation to ensure that yeast cells are supplemented with satisfactory levels of nutrients prior to fermentation. Although these actions aim to guarantee that yeast cells are healthy and active from the early stages of the fermentation, some of these supplements may be superfl uous.…”