bruxellensis or the Kwkt. The growth curves of the viable D. bruxellensis cells in the must microfermentations are shown in Fig. 2. In the positive control without Kwkt and without addition of SO2, the D. bruxellensis maintained the initial concentration until day 4, after which the biomass increased by about one logarithmic order (from 103 to 104 cells mL−1) over the course of the microfermentations to the end of the fermentation. As expected, in the presence of SO2, a rapid death

rate for the D. bruxellensis was learn more seen (no viable cells by the fourth day; Fig. 2). The D. bruxellensis growth curve in the presence of both concentrations of purified Kwkt (40 and 80 mg L−1, 12 and 24 AU mL−1, respectively) showed similar behaviour to that seen after the addition of SO2. Indeed, under these conditions, Kwkt showed effective control of the D. bruxellensis spoilage yeast: at the higher Kwkt concentration (80 mg L−1) the sensitive D. bruxellensis also disappeared by the fourth day, and by seventh day with Kwkt at the lower concentration (40 mg L−1). These results are comparable to those

obtained in the wine environment in a previous work using partially purified Kwkt (Comitini et al., 2004a). The well-test assay of the must was carried out throughout the full fermentation process. The results indicated that with both these added Kwkt Selleck GSK1120212 concentrations also there was zymocidial activity during the first stages of the fermentation. Indeed, the activity persisted in the must at least for 4 days at the lower Kwkt concentration (40 mg L−1), and at least for 7 days at the higher Kwkt concentration (80 mg L−1; Fig. 2). The results of the chemical analyses for the most important undesired enological characters of these microfermentations are reported in Table 2. In

the positive control without Kwkt and without SO2, D. bruxellensis produced volatile compounds. These levels were not affected by the use of SO2 or the addition of the lower concentration (40 mg L−1) of Kwkt. Interestingly, when Kwkt was added at the higher concentration (80 mg L−1), the acetic acid content, evaluated as volatile acidity, decreased significantly (P<0.01) vs. all other conditions. For the 4-ethyl phenol production, the positive control without Kwkt and without SO2 showed the highest levels of 4-ethyl phenol (0.140 mg L−1), whereas in the presence of both 40 and 80 mg L−1 Kwkt, no ethyl phenols were produced. A low production of 4-ethyl phenol was seen in the trials where 60 mg L−1 SO2 was added. In this study, we have described the purification and the activity in wine of the killer toxin produced by K. wickerhamii, Kwkt, which is active against Brettanomyces/Dekkera spoilage yeasts.