Use of L-rhamnose to study irreversible adsorption of bacteriophage PL-1 to a strain of Lactobacillus casei.

L-rhamnose has been found to be useful to investigate the process of irreversible adsorption of PL-I phage to its host bacterium, Lactobacillus casei ATCC27092. L-rhamnose inhibited phage adsorption to cells without inactivating free phages. Adsorption inhibition was correlated with the concentrations of L-rhamnose. The inhibitory effect of L-rhamnose on phage adsorption was of a competitive nature against host cells. Among other saccharides tested, L-fucose, L-mannose and D-ribose showed a slight degree of adsorption-inhibiting activity. In early stages of phage adsorption in a tris-maleate buffer, where the binding of phages to cells was still reversible, addition of L-rhamnose resulted in the partial desorption of phages from the cells to which they had adsorbed. However, the number of infective phages desorbed by L-rhamnose treatment gradually fell off as incubation continued, showing that the phages became firmly bound to the cells. Therefore, it is possible to determine the number of phages irreversibly adsorbed to cells by using this desorption technique with L-rhamnose. The process of irreversible phage adsorption, that is, the formation of phage-cell complexes from which no more infective phages could be desorbed, was dependent on temperature and strongly inhibited at 0 degrees C.