The Oleaginous Yeast Metschnikowia pulcherrima Displays Killer Activity against Avian-Derived Pathogenic Bacteria

<i>Metschnikowia pulcherrima</i> is a non-conventional yeast with potential to be used in biotechnological processes, especially those involving low-cost feedstock exploitation and biocontrol applications. The combination of traits that supports these industrial applications in <i>M. pulcherrima</i> also makes it an attractive option to study in the context of livestock health. In this study, we examined the specific interactions between <i>M. pulcherrima</i> and multiple avian pathogenic bacteria. We tested individual bacteria-yeast interactions and bacterial combinations in both solid and liquid media and in variable nutrient environments. Across multiple isolates of <i>M. pulcherrima</i>, we observed different levels of antimicrobial activity, varying from supporting the growth of competing bacteria through suppression and bacterial killing, and we found that these responses varied depending on the bacterial strains and media. We identified multiple molecular routes, including proteins produced by <i>M. pulcherrima</i> strains, that acted to control these microbial interactions. Furthermore, protein screening revealed that <i>M. pulcherrima</i> strains were induced to produce proteins specifically when exposed to bacterial strains, suggesting that fine-tuned mechanisms allow <i>M. pulcherrima</i> to function as a potential lynchpin in a microbial community.