PROTEIN CHARACTERIZATION OF LACTOCOCCUS-LACTIS SSP LACTIS AND L-LACTIS SSP CREMORIS BACTERIOPHAGES ISOLATED FROM CHEESE WHEYS

Proteins of Lactococcus lactis ssp. lactis and L. lactis ssp. cremoris bacteriophages were studied using antibody inhibition assay and immun oblotting. Antisera were prepared against four representative L. lacti s ssp. lactis and L. lactis ssp. cremoris phages (D59-1, F4-1, G72-1, and I37-1), which were selected from 17 isolates, derived from commerc ial cheese wheys. The reactivities of the four antisera with 13 other phage isolates were tested. Among these isolates, two phage groups hav ing distinct serological properties were found. Group I reacted with t he antisera against phages D59-1/F4-1 and group II reacted with the an tisera against phages G72-1/I37-1. Strongly lytic phages, capable of l ysing phage-resistant host strains, were found to share protein simila rities with the phage protein group I, and phages isolated from phage- sensitive host strains belonged to the phage protein group II. Further more. group I was composed of all prolate and some isometric phages, w hereas group II was composed solely of the isometric phages. Thus, the two serologically distinct phage groups were not correlated with the two morphological groups, prolate and isometric. Proteins of the four phages were further characterized by immunoblotting and silver stainin g. A 22.5-kDa antigenic polypeptide of phage I37-1, and three polypept ides of 65, 37, 21 kDa in phage F4-1 were responsible for the cross-re activities in group II and group I, respectively.