Breast milk samples were collected from seven healthy mothers
in sterile bags and stored at 4 C until used for isolation. Bacterial
isolation was performed according to a method of Harrigan and
McCance (1990, p. 452). Briefly, tryptone glucose yeast extract
(TGYE) medium prepared from formulation was used for the
growth of bacterial cultures and 48 h of incubation at 37 C was
chosen for the isolation step. Stock cultures of the strains were
maintained at 20 C in TGYE broth containing 20% (v/v) glycerol