MOLECULAR-GENETICS OF BACTERIOPHAGES OF LACTIC-ACID BACTERIA

Bacteriophage infection of lactic acid bacteria starter cultures can r esult in serious disruption or even failure of fermentation processes. With the help of newly developed techniques, progress has been made i n the molecular characterisation of phages of lactic acid bacteria (LA B) and also in the elucidation of the nature of their interaction with host cultures. A number of receptors involved in phage adsorption hav e been indentified and DNA penetration and injection, as well as the i ntracellular development of the LAB phages have been investigated. The structural organisation of Lactobacillus and lactococcal phage genome s have also been determined and a number of phage genes has been clone d and sequenced. These include determinants for phage lysin and phage structural proteins. Specific loci, attachment sites (att), involved i n the integration of temperate phage genomes, the cohesive ends (cos), involved in phage genome circularisation and the packaging sites (pac ) of circularly permuted phages have been localised and in many cases characterised at a molecular level.