Saccharomyces and Oenococcus

The interactions between Saccharomyces 3.nd O. during vinification may be either stimulatory (Liithi and Vetsch, 1959 Beelman etal., 1982 Feullat et al., 1985 Guilloux-Benatier et al., 1985) or inhibitory (Beelman et al., 1982 King and Beelman, 1986 Cannon and Pilone, 1993 Henick-Kling and Park, 1994 Larsen et al., 2003) to the bacterium. Inhibitory interactions have been reported where the viability of O. oeni declined from 10 to lO CFU/mL to undetectable populations soon after inoculation into wine (Fornachon, 1968 Beelman et al., 1982 Liu and Callander, 1983 Ribereau-Cayon, 1985 King and Beelman, 1986 Lemaresquier, 1987 Wibowo et al., 1988 Semon et al., 2001). This rapid decline in bacterial viability has been frequently reported, even when Saccharomyces and O. oeni are co-inoculated at similar population densities (Fig. 6.4). 

More recent studies have demonstrated that the removal of nutrients by yeast does not always explain the observed inhibition of O. oeni. For instance, Larsen et al. (2003) reported that the addition of supplemental nutrients to a wine fermented by S. cerevisiae strain V1116 did not relieve the observed bacterial inhibition. Studying the impact of yeast autolysis on MLF, Patynowski et al. (2002) also concluded that nutrient depletion by S. cerevisiae was not responsible for the observed bacterial inhibition. Furthermore, this research showed that the yeast produced an unidentified inhibitory factor(s) that was progressively lost during aging. These results suggested that the second proposed theory, the production of toxic metabolites by yeast, may be responsible for the inhibition of O. oeni. 

Wine yeasts are known to produce compounds during alcoholic fermentation that are inhibitory to malolactic bacteria including ethanol (Costello etal., 1983 Davis etal., 1986a Britz and Tracey, 1990), SO2 (Eschenbruch, 1974 Dott et al., 1976 Eschenbruch and Bonish, 1976 Suzzi et al., 1985 Romano and Suzzi, 1993 Henick-Kling and Park, 1994 Larsen et al., 2003), medium-chain fatty acids (Edwards and Beelman, 1987 Lonvaud-Funel et al., 1988 Edwards et al., 1990 Capucho and San Ramao, 1994), and antibacterial proteins/peptides (Dick et al., 1992). Of these 

Another theory for inhibition of malolactic bacteria was suggested by Wibowo et al. (1988) who proposed that S. cerevisiae may inhibit O. oeni through the yeast production of antibacterial proteins/peptides. In support, Dick et al. (1992) isolated two proteins produced by S. cerevisiae that showed activity against O. oeni. Osborne (2005) was able to isolate a 

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