Prevention of aerobic spoilage of maize silage by a genetically modified killer yeast, Kluyveromyces lactis, defective in the ability to grow on lactic acid

In this study, we propose a new process of adding a genetically modified ki ller yeast to improve the aerobic stability of silage. Previously construct ed Kluyveromyces lactis killer strain PCK27, defective in growth on lactic acid due to disruption of the gene coding for phosphoenolpyruvate carboxyki nase, a key enzyme for gluconeogenesis, inhibited the growth of Pichia anom ala inoculated as an aerobic spoilage yeast and prevented a rise in pH in a model of silage fermentation. This suppressive effect of PCK27 was not onl y due to growth competition but also due to the killer protein produced. Fr om these results, we concluded that strain PCK27 can be used as an additive to prolong the aerobic stability of maize silage. In the laboratory-scale experiment of maize silage, the addition of a killer yeast changed the yeas t flora and significantly reduced aerobic spoilage.