Bacteriophages Infecting Lactic Acid Bacteria

Lactic acid bacteria (LAB), such as Lactococcus lactis, Streptococcus thermophilus, Lactobacillus species, and Leuconostoc species are required for the production of a variety of fermented dairy products including cheese, yoghurt, and buttermilk. Despite extensive control measures, these LAB are frequently targeted by bacterial viruses, better known as (bacterio)phages, which can have a detrimental impact on product quality and yield. Classification of LAB phages was routinely based on morphology, serology, and DNA hybridization. Advances in genome sequencing and protein characterization technologies have enabled the development of a coherent classification scheme of LAB-infecting phages, and have further enhanced our understanding of phage-host interactions. This chapter discusses morphological features, genomics, and classification of currently recognized LAB phage groups, as well as the phage life cycle, phage-resistance mechanisms, and strategies to control or prevent phage proliferation in a dairy plant.