Application of the extracellular α-amylase gene from Streptococcus bovis 148 to construction of a secretion vector for yogurt starter strains

Abstract

Streptococcus thermophilus ATCC 19288, Lactobacillus delbrueckii subsp. bulgaricus T-11, and Lactococcus lactis subsp. lactis IL1403 were transformed with the α-amylase gene (amyA) from Streptococcus bovis 148 by using a wide host-range vector, and all the transformants secreted the α-amylase successfully. Since the promoter and the secretion signal of the amyA gene were functional in these strains, we constructed a secretion vector using the expression elements of amyA. Trials to secrete foreign enzymes in yogurt starter strains were performed using this novel secretion vector.