bacteriophages and their bacterial hosts is very important. The dairy fermentation industry has openly acknowledged the problem of phage contamination, and has worked for decades with academia and starter-culture manufacturers to develop defence strategies and systems to curtail phages' propagation and evolution. Bacteriophage–host interaction The first contact between an infecting phage and its bacterial host is the phage's attaching to the host cell. This attachment is mediated by the phage's receptor binding protein (RBP), which recognizes and binds to a receptor on the bacterial surface. RBPs are also referred to as host-specificity proteins, host determinants, and antireceptors. A variety of molecules have been suggested to act as host receptors for bacteriophages infecting LAB; among those are polysaccharides and (lipo)teichoic acids, as well as a single-membrane protein. A number of RBPs of LAB phages have been identified by the generation of hybrid phages with altered host ranges. These studies, however, also found additional phage proteins to be important for successful phage infection. Analysis of the crystal structure of several RBPs indicates that these proteins share a common tertiary folding, and support previous indications of the saccharide nature of the host receptor. Gram-positive LAB have a thick peptidoglycan layer, which must be traversed to inject the phage genome into the bacterial cytoplasm. Peptidoglycan-degrading enzymes are expected to facilitate this penetration, and such enzymes have been found as structural elements of a number of LAB phages. Lactic acid bacteria and dental plaque LAB are able to synthesize levans from sucrose, and dextrans from glucose. Dextrans, like other glucan, enable bacteria to adhere to the surface of teeth, which in turn can cause tooth decay through the formation of dental plaque and production of lactic acid. While the primary bacteria responsible for tooth decay is Streptococcus mutans, LAB do feature among the other most common oral bacteria that cause decay. Lactic acid bacteria genera Abiotrophia Aerococcus Carnobacterium Enterococcus Lactobacillus Lactococcus Leuconostoc Oenococcus Pediococcus Streptococcus Tetragenococcus Vagococcus Weissella See also Gaffkaemia Malolactic fermentation Lactic acid fermentation Lacto-2 RNA motif References Further reading External links Lactic Acid Bacteria at MetaMicrobe: taxonomy, facts, probiotic properties, and references Bacilli Gram-positive bacteria sv:Lactobacillaceae