Propolis as a potential alternative for the control of Dekkera bruxellensis in bioethanol fermentation

LETICIA A. FERNÁNDEZ; IRENE L. CIBANAL; ANNA L. PARALUPPI; CAROLINE DE FREITAS; LILIANA M. GALLEZ; SANDRA R. CECCATO-ANTONINI

SEMINA

UNIV ESTADUAL LONDRINA

Año: 2019 vol. 40 p. 2071 - 2078

1676-546X

Dekkera bruxellensis is one of the most important contaminant yeasts of the alcoholic fermentation. The use of propolis which can selectively target the contaminating yeast but not the starter one, Saccharomyces cerevisiae, could be a useful nonconventional strategy to control contaminant yeasts. The objective of this work was to evaluate four samples of propolis produced by Apis mellifera honeybeesfrom different regions of Argentina as antimicrobial agent on the growth of D. bruxellensis and S. cerevisiae.Hydroalcoholic extracts of propolis were prepared with ethanol : water (70:30 v/v) and the specific absorbancies as well as the final concentration of the samples were evaluated. A qualitative in vitro assay in solid medium was performed with different propolis concentrations and the evaluation of yeast growth was based on a qualitative scale. A quantitative in vitro assay in liquid medium was performed by using two different propolis concentrations and the yeast cell number was assessed. The number of D. bruxellensis decreased 1.52 and 1.85 log cycles with the two propolis extracts utilized at the concentration of 4.5 mg mL-1 while the cell number of S. cerevisiae decreased 0.48 ? 0.76 log cycles with the same samples of propolis. The results from both assays demonstrated the selectivity of propolis on the yeast species, especially on the greater inhibition of D. bruxellensisgrowth. This indicates the good prospect of using propolis as a nonconventional strategy to control the growth of D. bruxellensis in the concentration of 4.5 mg mL-1 without affecting S. cerevisiae substantially.