INVESTIGADORES
MENDOZA Lucia Margarita
congresos y reuniones científicas
Título:
Killer yeasts as biocontrol agents of spoilage yeasts and bacteria isolated from wine
Autor/es:
MIGUEL FERNÁNDEZ DE ULLIVARRI; LUCÍA M. MENDOZA; RAÚL R. RAYA
Lugar:
Mendoza
Reunión:
Congreso; 37th World Congress of Vine and Wine; 2014
Institución organizadora:
OIV
Resumen:
During the winemaking
process there is a predominance of fermentative yeasts as Saccharomyces
cerevisiae, which are used as starter cultures. However,
during fermentation other yeasts called non-Saccharomyces as well as
different species of lactic acid bacteria (LAB) are also present. Yeasts of the
genera Dekkera/Brettanomyces as well as Pichia guilliermondii
and P. membranifaciens are generally considered wine contaminants during
the fermentation stage or post-fermentation. On the other hand, among wine LAB Lactobacillus
hilgardii and Pediococcus pentosaceus are also considered
undesirable bacteria mainly for its ability to produce biogenic amines,
compounds that affect the sanitary and sensory quality of wines. One strategy
to prevent or reduce microbial contamination during the winemaking process is
the use of killer yeasts. These yeasts produce proteic toxins that inhibit the
growth of unwanted yeasts and fungi, but its effect on LAB has not been
reported yet. The aim of this study was to evaluate the killer activity (KA) of
autochthonous yeasts from Northwest region of Argentine, S. cerevisiae Cf8
and Wickerhamomyces anomalus Cf20 on different strains of spoilage yeasts
and LAB of wine.
The KA was evaluated
using cell-free supernatants obtained from pure and mixed cultures of strains Cf8-Cf20
in YPD medium (pH 4.0, 20 ° C, 96 h). As control, the supernatant treated at
100 ° C for 1 hour to denature the toxin was used. The spoilage yeasts studied
were: B. bruxellensis Ld1, D. anomala
BDa15, P. membranifaciens BPm481, P. guilliermondii Cd6, Schizosaccharomyces pombe BSp399, Zygosaccharomyces bailii Ld2 and Z. bailii Bzb317.
The killer supernatants
were inoculated with 5x106 cfu / ml, incubated at 20 ° C for 48 h
and growth inhibition was assessed by OD 600nm reading. The KA was calculated
as % growth reduction in relation to the control. To study KA on LAB a
screening was carried out in MRS agar medium using supernatants of each yeast
10x concentrated by ultrafiltration (Amicon 30 kDa) on a lawn of each LAB. In
addition, the effect of the killer supernatants of each strain and co-culture
Cf8-Cf20 on L. hilgardii growth and histamine production by RP-HPLC was evaluated.
S. cerevisiae Cf8
supernatant produced a growth reduction between 10 and 35% on D. anomala BDa15, P. membranifaciens BPm481, P.
guilliermondii Cd6 and Z. bailii Bzb317 while
W. anomalus Cf20 exhibited KA of 20, 61 , 91 and 92% against B.
bruxellensis Ld1, D. anomala BDa15, P. membranifaciens BPm481y P.
guilliermondii Cd6, respectively. Killer
mixed supernatants showed growth inhibition similar to strain Cf20. Screening
against LAB showed that the killer toxins were able to inhibit the growth of L.
hilgardii 5w, strain producing histamine. When KA of Cf8 and Cf20 supernatants
was evaluated on this bacterium, it was observed a longer lag phase and lower final
growth as well as a 16-31% decrease in biogenic amine production by this
strain, being higher the inhibitory effect in presence of both killer toxins.
These results confirm the
potential of autochthonous killer yeasts as biocontrol agents in winemaking
process. The mixed culture S. cerevisiae Cf8-W. anomalus Cf20 presented
a wide range of KA on spoilage yeasts as well as on L. hilgardii.
Therefore, the use of killer yeasts as starter cultures would permit to produce
wines with controlled quality.