Characterization of receptor sites for bacteriophages PL-1, J-1 and MLC-A using two strains of Lactobacillus casei

Abstract

Receptor sites and adsorption process of two collection phages and the first Argentinian indigenous Lactobacillus paracasei bacteriophage (MLC-A), on purified cell walls were characterized. To identify the nature of receptors, thermal, enzymatic and chemical treatments were performed on L. casei purified cell walls. Differences found between adsorption on whole or fragments of cells indicated that cell walls wereefficient for phage adsorption, but its receptors were not as complete as in whole cell. Adsorption of phages was not influenced by sodium dodecyl sulphate and proteinase K treatments, butdecreased when cell walls were previously incubated with mutanolysin or trichloroacetic acid, suggesting that receptors were carbohydrates in nature. L-rhamnose was implicated as a receptor component for the collection phages on L. casei ATCC 393 and also as a major component for phage MLC-A on L. casei ATCC 27139. In the latter case, L-ribose seemed to play an important role in adsorption process. This study suggested possible existence of an equilibrium state between phage adsorption to and its release from cell walls, questioning the integrity of receptor sites on cell walls.