Growth of L. delbrueckii subsp. bulgaricus was initially
slower in soy beverage than in cows' milk. This was expected,
because most L. delbrueckii subsp. bulgaricus strains do not
grow well in soy beverages (Mital et al., 1974; Karleskind
et al., 1991; Murti et al., 1993b). However, after 4 h incubation,
growth of the organism improved significantly. That
could be due to the faster drop of the pH of soy beverage than
of cows' milk, to pH values which are favourable to the
growth of lactobacilli. These data suggest that some of the
symbiotic elements of the relationship between the two yogurt
strains, which are well documented in milk fermentation
(Tamime and Robinson, 1985), might occur in the soy beverage
also.