Metschnikowia pulcherrima

Metschnikowia pulcherrima is a ubiquitous species of yeast, with numerous strains, belonging to the family Metschnikowiaceae, and found on grapes, cherries, flowers, spoiled fruit and consequently carried by fruit flies. It is a non-Saccharomyces yeast and plays an important role in the vinification of wine when it is present on grapes or winery equipment, and has historically seen use in South Africa’s wine industry. It is also being studied at the University of Bath as a possible alternative to the use of Palm oil, and early results show promise. M. pulcherrima is ovoid to ellipsoidal in shape and reproduces by budding. Its cells are globose and thick-walled, holding a single, large oil droplet of high refractive index. As the result of incomplete budding where cells remain attached after division, pseudohyphae may form under anaerobic conditions.

The strains of M. pulcherrima show strong biocontrol activity against various microorganisms. Its value to the wine industry lies in its antagonistic behaviour to other, undesirable yeast species involved in winemaking. In a 2014 study 7 strains of M. pulcherrima were examined for their activity against a large range of yeast strains including Pichia, Candida, Hanseniaspora, Kluyveromyces, Saccharomycodes, Torulaspora, Brettanomyces and Saccharomyces genera. A variety of inter-generic and intra-generic interactions were observed.