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

Abstract

Lactobacillus vini was recently described as a contaminant in industrial ethanol fermentations and its co-occurrence with Dekkera bruxellensis was noted. We investigated the growth characteristics of L. vini in cocultivation together with either Saccharomyces cerevisiae or D. bruxellensis. Lower cell numbers of both the yeasts and L. vini as well as a decrease in ethanol and lactate formation in mixed batch cultures compared with pure cultures were noted. L. vini formed cell aggregates (flocs) in all cultivation media with different shapes in Man–Rogosa–Sharpe and yeast extract–peptone–dextrose media. Flocs’ size and proportion of cells bound to flocs increased with increasing ethanol concentration. In coculture, formation of lactic acid bacteria–yeast cell aggregates consisting of a bacterial core with an outer layer of yeast cells was observed. L. vini–D. bruxellensis flocs had a bigger surface, due to cells protruding from the pseudomycelium. The involvement of mannose residues in the flocculation between L. vini and yeasts was tested. The presence of mannose induced deflocculation in a concentration-dependent manner. Less mannose was required for the deflocculation of D. bruxellensis as compared with S. cerevisiae.

Saccharomyces cerevisiae transcriptional reprograming due to bacterial contamination during industrial scale bioethanol production

“…Lactobacillus species are the main bacterial contaminants found in sugarcane bioethanol production due to their ability to tolerate ethanol stress [8 - 11% (v/v)] and the anti-bacterial acid wash administered to the yeast cells prior to pitching each new batch (pH 2.0 – 3.0) [ 9 ]. L. fermentum , L. vini and L. plantarum , have been reported to be the main agents responsible for the co-aggregation of yeast cells [ 10 , 11 ]. The mannose-specific adhesin (Msa) found in L. plantarum and L. fermentum has been implicated in cell-cell interactions [ 12 - 14 ].…”

Anti-Contamination Strategies for Yeast Fermentations

“…The acidic products cause a decrease in sugar consumption, growth inhibition of S. cerevisiae, and a decrease in ethanol production [64]. If S. cerevisiae is contaminated by L. fermentum, flocculation (co-aggregation) of S. cerevisiae with L. fermentum can occur [65][66][67]. S. cerevisiae-L. fermentum flocculant produces organic acids at a higher level than axenic S. cerevisiae [68].…”

Saccharomyces cerevisiaemetabolism in ecological context

“… 2014 ) and biofuel production cultures (Watanabe, Nakamura and Shima 2008 ; Lucena et al . 2010 ; Tiukova, Eberhard and Passoth 2014 ). Lactic acid bacteria (LAB) are commonly found together with S. cerevisiae in the domestic applications (e.g.…”

“…Furthermore, LAB are common spoilage organisms in open S. cerevisiae fermentations used for biofuel production (Watanabe, Nakamura and Shima 2008 ; Lucena et al . 2010 ; Tiukova, Eberhard and Passoth 2014 ). In bioethanol production, Lactobacillus fermentum and L. brevis have been reported as the most common contaminants (Watanabe, Nakamura and Shima 2008 ).…”