Antimicrobial activity ofMetschnikowia pulcherrimaon wine yeasts

Abstract

Aims: In the present study, it was investigated the antagonistic behaviour of Metschnikowia pulcherrima, as biocontrol agent, against the main wine yeast species involved in the winemaking process. Methods and Results: Seven strains of M. pulcherrima were evaluated for the antimicrobial activity against 114 yeast strains belonging to Pichia, Candida, Hanseniaspora, Kluyveromyces, Saccharomycodes, Torulaspora, Brettanomyces and Saccharomyces genera. Results showed both different inter-generic and intrageneric responses to the antimicrobial action of M. pulcherrima strains. Interestingly, the antimicrobial activity of M. pulcherrima did not have any influence on the growth of Saccharomyces cerevisiae. Instead, M. pulcherrima displayed a broad and effective antimicrobial action on undesired wild spoilage yeasts, such as Brettanomyces/Dekkera, Hanseniaspora and Pichia genera. Fermentation trials carried out in synthetic grape must confirmed the antimicrobial activity of M. pulcherrima, determining the early death of the non-Saccharomyces co-inoculated cultures. Conclusions: The antimicrobial activity of M. pulcherrima does not seem due to proteinaceous compounds such as killer phenomenon, but to the pulcherriminic acid (the precursor of pulcherrimin pigment) that depletes iron present in the medium, making it not available to the other yeasts. Significance and Impact of the Study: These data agree with and further support the potential use of selected M. pulcherrima strains in controlled multistarter fermentations with S. cerevisiae starter cultures.

Microbial Resources and Innovation in the Wine Production Sector

“…These studies demonstrated that non-Saccharomyces species could have both beneficial and negative influences on the wine fermentation characteristics, thus indicating the need to select strains with optimal oenological properties (Bely et al, 2008;Comitini et al, 2011;De Benedictis et al, 2011;Medina et al, 2012;Lu et al, 2015;Petruzzi et al, 2017a). Indeed, several non-Saccharomyces species have been proven to positively modify the wine chemical composition, contributing especially to the sensory properties of wines (Jolly et al, 2014;Oro et al, 2014;Lu et al, 2015;Petruzzi et al, 2017a). However, the growth of certain non-Saccharomyces strains in grape musts can cause the development of antagonistic interactions among yeasts and lead to an excessive accumulation of several undesirable metabolites, such as acetic acid, ethyl acetate, aldehyde and acetoin (Medina et al, 2012;Ciani et al, 2016;Liu et al, 2017), and other phenotypic properties in some cases also characteristic to S. cerevisiae strains from alcoholic beverages .…”

“…To control the proliferation of this yeast, sulphur dioxide is commonly employed, but the efficiency of this chemical compound is subject to wine composition and it can also elicit allergic reactions in humans. Biological alternatives, such as the use of starter cultures as biocontrol agents (García-Moruno & Muñoz, 2012;Oro et al, 2014), are therefore actively sought.…”

Non-Saccharomyces Killer Toxins: Possible Biocontrol Agents Against Brettanomyces in Wine?

“…Chitosan, the deacetylated derivative of chitin, was found to have a fungistatic effect against B. bruxellensis and, at concentrations > 3 g/L, the yeast ceased to survive (Gómez-Rivas et al, 2004). Recently, Oro et al (2014) showed that Metschnikowia pulcherrima secretes pulcherriminic acid, which is inhibitory to the growth of B. bruxellensis. Finally, in recent studies, the use of biological antimicrobial compounds, such as the killer toxins Kwkt, Pikt and PMKT2 from the yeast species K. wickerhamii, P. anomala and P. membranifaciens respectively, was shown to be successful in inhibiting Dekkera/Brettanomyces in wine, and these will be discussed in the next section.…”

Directed metabolomic approaches for the characterization and development of new yeast strains

“…Scientific works about these two species are abundant [7,[39][40][41][42], being the most common non-Saccharomyces species commercially available for wine industry besides Torulaspora delbrueckii strains [10,43,44]. T. delbrueckii showed a low implantation rate in fresh must but, due to its high fermentation power and ethanol tolerance (9-11%), it is one of the non-Saccharomyces yeasts with higher incidence on wine properties and quality.…”

“…Another point of interest is the production of pulcherrimin pigment that causes certain antimicrobial effect on the other yeast populations, including the spoilage yeast Brettanomyces bruxellensis [39]. Apart from that, the notable implantation of M. pulcherrima during wine fermentation, when it is used in sequential fermentation with S. cerevisiae, causes its incidence in volatile compounds of wines producing high concentrations of esters [60,61].…”