Study on key enzymes involved in producing lactic acid of Lactobacillus delbrueckii subsp.Bulgaricus

Four Lactobacillus delbrueckii subsp.bulgaricus strains were regarded as the research subject, studied the enzymes of metabolic pathway from lactose to lactic acid and H～+-ATPase, to find which enzyme was the most important one that results in postacidification of yogurt, and the reason why KLDS1.1006 ang KLDS 1.1011 had a weak postacidification character.The key enzymes of Lactobacillus delbrueckii subsp.bulgaricus played important roles in producing lactic acid wereβ-galactosidase and H～+-ATPase.Lactate dehydrogenase and protease showed no obvious correlation with postacidification.The enzyme activities ofβ-galactosidase and H～+-ATPase were weak, which was the fundamental reason why KLDS1.1006 and KLDS 1.1011 reflected weak postacidification.