Phages of yeast and bacteria

Abstract

Toxin-secreting killer yeasts of a great variety of genera including Saccharomyces, Hanseniaspora and Zygosaccharomyces are not only frequently present on grapes, they often also cause severe stuck fermentations. Since virus-infected killer strains of the wine yeast Saccharomyces cerevisiae are best studied among killer yeasts, the present chapter will summarize the most recent advances in killer yeast biology with special emphasis on yeast virology, killer toxin action and toxin immunity. Although still controversial, phage attack on wine bacterial strains may be a source of malolactic failure during winemaking. This possibility opened the way to the characterization of phages infecting Oenococcus oeni. Molecular biology studies have centered on phage genes involved in prophage integration and on the determinants of lysis. Multiple tRNA genes appear to be targets of prophage integration in Oenococcus. Molecular studies also revealed that peptidoglycan hydrolases of phage origin may be endowed with secretion signals, a feature previously undescribed for bacteriophage endolysins. © 2009 Springer-Verlag Berlin Heidelberg. All rights reserved.