Serial tenfold
dilutions were prepared in a solution of 0.9% NaCl (w/v) and
0.1% (w/v) bacto peptone (Difco) and suitable dilutions were
plated on appropriate media. L. delbrueckii subsp. bulgaricus
were enumerated on lactobacilli MRS broth (Difco) supplemented
with agar, 15 g/l (Difco); S. thermophilus were enumerated on
M17 broth (Difco) supplementedwith lactose, 5 g/l