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Andrea Caridi, Rossana Sidari
Laboratory oJ Microbiology, Department STAFA,Faculty of Agriculture, "Mediterranea"
University oJReggio Calabria, Reggio Calabria, Italia
acaridi@unirc. it
There is wide evidence for the effects of nutrient depletion on fungal cell wall, as the pseudohyphal growth and the flocculation state in Saeeharomyees cerevisiae. The present work
aimed to describe the effect of carbon and nitrogen availability on parietal adsorption activity
of selected wine yeasts, testing them in the presence of grape pigments. Eleven strains of S. cerevisiae - previously selected as wine starter also considering their different aptitude to adsorb
grape pigrnents - and the contro lstrains of S. cerevisiae BY4742 and L:1278bwere grown on (a) grape skin agar (1), containing black grape skin powder 4% and dextrose 5%, 2% or 0.1%, (b) synthetic low ammonium dextrose agar (2) supplemented with black grape skin powder 4% and containing dextrose 2% or 0.1%, and (e) yeast peptone dextrose agar as control medium. After incubation at 28°C for lO days, strains were processed for their colour components by Photoshop
CS (l), that gives low or high values for yeast able (dark biomass) or unable (light biomass) to
adsorb coloured compounds, respectively. In the different growth conditions, the tested yeasts showed wide and significant differences for their colour components. In general, depletion in
(a) nitrogen or in (b) earbon and nitrogen determines adecrease in the yeast adsorption activity.
The relevant related literature and the present results are discussed considering, above all, the
oenological consequences for wine starter selection.
(l) Caridi A. et al. - Wine colour adsorptionphenotype: an inheritable quantitative trait lociof yeasts. JoumalofApplied Microbiology 103,735-742,2007.
(2) Zaragoza O., Gancedo lM. - Pseudohyphal growth is induced in Saccharomyces cerevisiae by a combination ofstress and cAMP signalling.Antonie van Leeuwenhoek78,187-194,2000.
Thisresearch was supported by Calabria Region, Research Fund APQ, Action 3, leader winery: Caparra &Siciliani.
