Yeast biofilm-like behaviour in rich or poor media in the presence of polyphenols.

IVlurcmationalCcnferenceon Environmcntaklndusrrial and Applied Microbiology (BioMieroWorld2011) Torremolinos(Spain),14-16 September2011

Yea

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biotiIm-lik

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behaviour in rich

or poor

media

in the

presence of pol

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phenols

R.Sidar!', K.S.Howell' andA.Caridi'

'Dcpartment of"Scienze eTecnologie Agro-Forestali e Ambientali", "Mediterranea" University ofReggioCalabria, Italy

'Department ofAgriculture and FoodSystems, Melboume SchoolofLand and Environment, University ofMelboume, Melboume, VIC,Australia

The yeast celi wall is adynamic strucrure in which changes in protein composition occur depending on nutrient availability and cnvironmental conditions. Celi wall mannoproteins are responsible both for yeast interaction with various environrnental substances, such aswine phenolic compounds, and celi-celi recognition events which

le ad yeast to grow as a biofilm, mat colonies, or display invasive and pseudohyphal forrns, here defined as biotilm-Iike behaviour. Significant differences incolour, polyphenolic index and anthocyanin content or wines fennented with different yeast strains ha ve been reported. The use ofrhe chromogenic medium Grape skin agar (Graski) to evaluate the aptitude ofyeasts to adsorb coloured phenolic compounds has allowed the inheritability ofthe trait Wine Colour Adsorption tobedernonstrated. Yeast biofilrn-like phenotypes depend 011theexpression ofthe fLO gene family butalsooncarbon andnitrogen availability.

The aim of this work was to study changes botb inyeast biofilm-Iike behaviour and in Wine Colour Adsorption ability inorder tounderstand thelinkbetween these phenotypes,

The study was carried out in rich orpoor media, concerning carbon and nitrogen concentration, supplemented with polyphenols. Eleven wine autochthonous Saccharomyces cerevisiae strains, belonging to the microbial collection of the Department of Scienze c Tecnologie Agro-Forestali e Ambientali, and two control strains S.

cerevisiaeLI278b, (MATa), which hasadhesive and filamentous phenotypes and S.cerevisiaeBY4742, (MATa,

1'.1108), which has a non-adhesive phenotype, belonging to the Departrnent of Agriculture and food Systems, were used. The srrains were tested for: a)biofilm formation insynthetic complete medium with 2% or 0.1% of dextrose, in Synthetic Low Ammonium Dextrose (SLAD) with 2% or0.1% of dextrose, and inthe same media supplernented with 100 mg/L of(+)-catcchin; b)invasive growth insolid YPD with 2% or0.1% ofdextrose, in solid SLAD with 2% or0.1% ofdextrose, inthe same media supplemented with 100 mgIL of(+)-catechin, and insolid Graski with 2% or 0.1% of dextrose, insolid SLAD with 2% or 0.1% of dextrose supplemented with skins from black grapes; c) growth asmat colonies inthe same media used for invasive growth but using 0.3% of agar; d)polyphenolic compound adsorption insolid Graski with 2% or0.1%ofdextrose and insolid SLAD with 2% or 0.1% of dextrose supplemented with skins from bìack grape .Inorder lo check the experimental condition influences onceli morphology, the strains were microscopically observed.

Results demonstrate that polyphenolic compounds modify in adifferent way the biofilm-Iike yeast phenotypes, and this behaviour varies amongst the yeast strains. The genetic basis of this difference is currently being explored and elucidated (fig. I). These phenotypes and the Winc Colour Adsorption phenotype could be considered not fully correlated strain-specific phenotypes, probably due totbe simultaneous or not presence of the responsible celiwall proteins which determines avariety ofphenotype combinations.

Keywords biofilm; polyphenols; wine colouradsorption; yeast celiwall

This research was supported by Calabria Region, Research Fund APQ, Action 3, "Miglioramento delle produzioni vitivinicole dellazona del Cirò", leaderwinery:Caparra& Siciliani.

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YPDZ% YPDO.l'" SLAD2%SLADO.l"

-c ec -c +C Fig.t- Invasive growth ofthe strainsScl321 in YPD and SLAD 2% or 0.1% of dextrose (on the lcft) and in the same media supplernented with 100mgIL of(+)-catechin - C - (on the right). Upper row: before washing plates; bottom row: footprints after

washing plates.

n02" TPDD.l" SLAD2" StAnO.I"