Activities of amylase, proteinase, and lipase enzymes from Lactococcus chungangensis and its application in dairy products

Several enzymes are involved in the process of converting milk to lactic acid and coagulated milk to curd and, therefore, are important in dairy fermented products. Amylase, proteinase, and lipase are enzymes that play an important role in degrading milk into monomeric molecules such as oligosaccharides, amino acids, and fatty acids, which are the main molecules responsible for flavors in cheese. In the current study, we determined the amylase, proteinase, and lipase activities of Lactococcus chungangensis CAU 28T, a bacterial strain of nondairy origin, and compared them with those of the reference strain, Lactococcus lactis ssp. lactis KCTC 3769T, which is commonly used in the dairy industry. Lactococcus chungangensis CAU 28T and L. lactis ssp. lactis KCTC 3769T were both found to have amylase, proteinase, and lipase activities in broth culture, cream cheese, and yogurt. Notably, the proteinase and lipase activities of L. chungangensis CAU 28T were higher than those of L. lactis ssp. lactis KCTC 3769T, with proteinase activity of 10.50 U/mL in tryptic soy broth and 8.64 U/mL in cream cheese, and lipase activity of 100 U/mL of tryptic soy broth, and 100 U/mL of cream cheese. In contrast, the amylase activity was low, with 5.28 U/mL in tryptic soy broth and 8.86 U/mL in cream cheese. These enzyme activities in L. chungangensis CAU 28T suggest that this strain has potential to be used for manufacturing dairy fermented products, even though the strain is of nondairy origin.