Effect of amino acids added to culture medium on the growth and survival of Lactobacillus bulgaricus LB6 during freeze-drying

Plackett–Burman design was applied to evaluate the effects of amino acids on the growth in medium and survival during freeze-drying of Lactobacillus bulgaricus LB6. Moreover, in consideration of the optimal amino acids for the growth and survival of Lactobacillus bulgaricus LB6 before and after freeze-drying, viable counts and survival rate were monitored in the medium containing selected amino acids (Glutamate, Alanine, Glycine, Leucine, Serine, Arginine, Lysine and Hydroxyproline). The results indicated that Leucine (p=0.0117 for viable counts, p=0.0121 for survival rate) and Arginine (p=0.0120 for viable counts, p=0.0043 for survival rate) out of the investigated amino acids can significantly affect both the growth and survival rate of Lactobacillus bulgaricus LB6, and have a positive effect.