PT  - JOURNAL ARTICLE
AU  - Roman Mink
AU  - Ralf Kölling
AU  - Stephan Sommer
AU  - Hans-Georg Schmarr
AU  - Maren Scharfenberger-Schmeer
TI  - Diacetyl Formation by <em>Oenococcus oeni</em> during Winemaking Induced by Exogenous Pyruvate
AID  - 10.5344/ajev.2014.14056
DP  - 2014 Oct 30
TA  - American Journal of Enology and Viticulture
PG  - ajev.2014.14056
4099  - http://www.ajevonline.org/content/early/2014/10/22/ajev.2014.14056.short
4100  - http://www.ajevonline.org/content/early/2014/10/22/ajev.2014.14056.full
AB  - Pyruvate is the central metabolite in diacetyl synthesis by Oenococcus oeni. Therefore, any substrate, which increases intracellular pyruvate concentration, can induce diacetyl accumulation. This study evaluates the effect of exogenous pyruvate on diacteyl formation and the expression of diacetyl related genes in Oenococcus oeni during winemaking. Diacetyl formation by Oenococcus oeni was induced by yeast derived pyruvate in the early stage of winemaking Furthermore, when additional pyruvate was added, α-acetolactate synthase (alsS) gene expression raised 1.6-fold and the diacetyl concentration increased from 0.4 mg/L to 2.3 mg/L. Although the highest alsS expression (10-fold) was found 24 h after pyruvate addition, no further increase in diacetyl concentration was found. In addition to that alsD was also overexpressed (9-fold) at that point, indicating that α-acetolactate was converted into acetoin. Altogether the results show that exogenous pyruvate induces diacetyl formation by Oenococcus oeni in the early state of winemaking. Furthermore pyruvate derived diacetyl is the result of a delayed alsD response which prevents acetoin formation.