Identification of compounds causing symbiotic growth ofStreptococcus thermophilusandLactobacillus bulgaricusin milk

Abstract
Strains of Lactobacillus bulgaricus and Streptococcus thermophilus isolated from yoghurt culture were used to study the cause of the synergistic effect on acid production by mixtures of the 2 cultures. The beneficial effect was essentially limited to the gradual accumulation of factors in the L. bulgaricus cultures that promoted more rapid acid production by Str. thermophilus. The active factors were identified as glycine and histidine.