High Titer, Phage-Neutralizing Antibodies in Bovine Colostrum that Prevent Lytic Infection of Lactococcus lactis in Fermentations of Phage-contaminated Milk

Abstract

Antibodies against six phages of Lactococcus lactis were produced in six bovine colostra. Each colostrum neutralized its homologous phage. In addition, each colostrum neutralized a different phage from the same species as its homologous phage, but either did not neutralize or weakly neutralized more distantly related lactococcal phages. The neutralization of heterologous phages correlated with the phage species but not with the strain on which the phage was grown. Blood serum from the same cows also neutralized homologous phages, but the titers were lower than that of the colostrum. Addition of colostrum to phage-contaminated milk prevented lysis of starter cultures of L. lactis. The titers of some of the colostra were sufficiently high that it may be economically practical to prepare antibodies from similar, high titer colostra for commercial use in factory bulk starter vats.