Characterization of strictly lytic phages infecting <i>Oenococcus oeni</i> from Merlot wines and proposal of a new genus

<i>Oenococcus oeni</i> is the predominant lactic acid bacteria species in wine, where it performs the malolactic fermentation, which helps to secure and preserve wine quality. Here, we describe the morphological, biological, and genomic characterization of siphophage Krappator X₂₇, a strictly lytic phage that was previously isolated from Merlot wines. Several aspects of the life cycle of the phage were investigated using the sensitive strain IOEBS277 under optimal growth conditions. X₂₇ has a large burst size (149 Plaque Forming unit [PFU] per infected cell) and targets industrially relevant strains of <i>O. oeni</i> used for production of wines. X₂₇ also shows lytic activity against its host in red and white grape juice media. The phage genome consists of 41,633 nucleotides. Structure prediction of the viral adhesion devices reveals elongated multi-domain machinery containing carbohydrate-binding modules likely involved in host recognition and binding. Genome-based phylogeny revealed that X₂₇ has less than 30% intergenomic similarities with its most similar phages and represents a new species in a yet unassigned genus, for which we propose the name « Krappavirus <i>»</i>. Aiming to expand the available collection of genomes in this genus, we sequenced two independently isolated phage homologs from Merlot wines. Modular protein evolution may play a role in the diversification of this specific phage lineage, and naturally occurring domain combinations were found in three crucial proteins of known function: the small terminase subunit, the endolysin, and the replisome organizer.IMPORTANCE<i>Oenococcus oeni</i> is commonly used for wine and cider production. Characterizing strictly lytic oenophages, understanding their genetic relationships, and studying their interactions with various hosts are the necessary steps for preventing and controlling phage attacks that occur along the fermentation process.