The consequences of Lactobacillus vini and Dekkera bruxellensis as contaminants of the sugarcane-based ethanol fermentation

Abstract

This work describes the effects of the presence of the yeast Dekkera bruxellensis and the bacterium Lactobacillus vini on the industrial production of ethanol from sugarcane fermentation. Both contaminants were quantified in industrial samples, and their presence was correlated to a decrease in ethanol concentration and accumulation of sugar. Then, laboratory mixed-cell fermentations were carried out to evaluate the effects of these presumed contaminants on the viability of Saccharomyces cerevisiae and the overall ethanol yield. The results showed that high residual sugar seemed the most significant factor arising from the presence of D. bruxellensis in the industrial process when compared to pure S. cerevisiae cultures. Moreover, when L. vini was added to S. cerevisiae cultures it did not appear to affect the yeast cells by any kind of antagonistic effect under stable fermentations. In addition, when L. vini was added to D. bruxellensis cultures, it showed signs of being able to stimulate the fermentative activity of the yeast cells in a way that led to an increase in the ethanol yield.

Distribution of Dekkera bruxellensis in a sugarcane-based fuel ethanol fermentation plant

“…; De Souza et al . ) and in Tabu distillery that has been affected by incidents of contamination in which D. bruxellensis cells were found in nearly 100% of the yeast population (De Souza et al . ).…”

“…) and in Tabu distillery that has been affected by incidents of contamination in which D. bruxellensis cells were found in nearly 100% of the yeast population (De Souza et al . ). However, it is difficult to extrapolate this hypothesis for distilleries affected by D. bruxellensis that use treated substrates such as corn mesh (Abbott et al .…”

Potassium metabisulphite as a potential biocide against Dekkera bruxellensis in fuel ethanol fermentations

“…; Souza et al . ). However, that yeast is involved in the production of volatile phenols in wines, with the formation of unpleasant odours that cause important economic losses in the wine industry (Oelofse et al .…”

“…Dekkera bruxellensis is a two-faced yeast to the fermentation industry. Due to its more efficient energy metabolism compared to Saccharomyces cerevisiae, ability to use nitrate as its sole nitrogen source, ability to produce ethanol under aerobic conditions and grow without oxygen, high tolerance to ethanol and acids and capacity to utilize a wide range of carbon sources, this yeast is considered a relevant ethanol-producing organism (Passoth et al 2007;Galafassi et al 2011Galafassi et al , 2013Blomqvist et al 2012;Souza et al 2012). However, that yeast is involved in the production of volatile phenols in wines, with the formation of unpleasant odours that cause important economic losses in the wine industry (Oelofse et al 2008).…”

Interaction of Lactobacillus vini with the ethanol‐producing yeasts Dekkera bruxellensis and Saccharomyces cerevisiae

“…It is currently unclear why D. bruxellensis so frequently co-occurs with L. vini in industrial ethanol fermentation 12. To investigate LAB–yeast interactions, cocultivations under conditions that are conducive to both microorganisms are required.…”