Analysis of exopolysaccharide (EPS) production mediated by the bacteriophage adsorption blocking plasmid, pCI658, isolated from Lactococcus lactis ssp cremoris HO2

Lactococcus lactis ssp. cremoris MG1363 harbouring pCI658, a 58 kb plasmid originating in L. lactis ssp. cremoris HO2, adsorbs phages phi 712 (936 pha ge species) and phi c2 (c2 species) less efficiently than the plasmid-free phage sensitive strain. The presence of an alkali-soluble loose 'fluffy' pe llet following centrifugation of the phage resistant derivative was establi shed. In addition this pCI658-containing strain possessed a more hydrophili c cell surface and did not agglutinate with the glucosyl-specific lectin co ncanavalin A. Furthermore, electron micrographs also illustrated significan t plasmid-mediated alterations of the cell surface. HPLC analysis of the lo osely associated extracellular material revealed that galactose and glucuro nic acid appeared to be its major components. It was concluded that pCI658 encodes the production of a hydrophilic exopolysaccharide which masks cell surface receptors causing a dramatic decrease in bacteriophage adsorption. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.