CONICET | Buscador de Institutos y Recursos Humanos

Understanding of the molecular mechanisms of bacteriophage interaction with their host bacteria can be used to develop strategies to avoid infections during dairy fermentation processes. We characterized the sub-cellular fractions involved in Lactobacillus casei phages J-1 and PL-1 recognition and adsorption. In other lactic acid bacteria, non-proteinaceous components of the cell wall have been described as receptors. Gram-positive bacteria surface may contain: (i) capsular polysaccharides (CPS) like rhamnose containing glycans (RWPS) often covalently bound to peptidoglycan (PG); (ii) wall polysaccharides (WPS) like Lipoteichoic acid (LTA) or wall teichoic acid (WTA) that may be or not covalently attached and (iii) extra-cellular polysaccharides (EPS) which are released into the cell environment. Each cell wall fraction was purified by different treatments to preserve their integrity and architecture and tested for phage adsorption inhibition. Total Cell Wall fraction (CW) contains all components; TCA soluble material retains WTA and/or RWPS. CW treated by boiling in 4% (w/v) SDS remove lipoteichoic acids and proteins living purified PG. D-alanine esters and O-acetylation were removed from CW by alkali. EPS was obtained from the culture supernatant. TCA soluble material efficiently block phage adsorption probably indicating the presence of phage receptors.