Novel Genus of Phages Infecting Streptococcus thermophilus: Genomic and Morphological Characterization
C. Philippe, Sébastien Levesque, Moïra B. Dion, Denise M. Tremblay, Philippe Horvath, Natascha Lüth, Christian Cambillau, Charles M. A. P. Franz, Horst Neve, Christophe Fremaux, Knut J. Heller, Sylvain Moineau
Abstract
Despite decades of research and adapted antiphage strategies such as CRISPR-Cas systems, virulent phages are still a persistent risk for the milk fermentation industry worldwide, as they can cause manufacturing failures and alter product quality. Phages P738 and D4446 are novel virulent phages that infect the food-grade Gram-positive bacterial species Streptococcus thermophilus . These two related viruses represent a fifth group of S. thermophilus phages, as they are significantly distinct from other known S. thermophilus phages. Both phages share similarities with phages infecting nondairy streptococci, suggesting their recent emergence and probable coexistence in dairy environments. These findings highlight the necessity of phage surveillance programs as the phage population evolves in response to the application of antiphage strategies.