Lactobacillus casei YIT 9018 의 세포내 단백질 분해효소에 관한 연구 = Studies on the Intracellular Proteinate of Lactobacillus casei YIT 9018

다국어 초록 (Multilingual Abstract)

Proteinase of lactic acid bacteria plays an important role in the development of the flavor and texture in cheese and in other fermented milk products. This study was carried out to obtain the informations on the intracellular proteinase of L. casei YIT 9018. Crude proteinase from L. casei YIT 9018 was isolated and characterized. The proteinase production was markedly increased during the logarithmic growth phase. The best proteinase production of L. casei YIT 9018 was obtained in the medium containing 2% of casein. The maximum proteinase production was observed at 37℃ and at pH 7.0. The proteolytic enzyme retained 74% of its original activity after heating at 60℃ for 60 min and 58% at 90℃ after 60 min. A metal chelating agent (EDTA) evidenced vity, but monoiodoacetic acid induced about 20% inhibition. Divalent Ni, Cu, Zn and Mg ions Caused 20-30% enzyme inhibition, while manganese ions enhanced the enzyme activity slightly. Further studies are needed for purification and characterization of the proteinase of L. casei YIT 9018. In addition, studies are needed to elucidate the proteolysis of milk protein by this proteinase during manufacture and ripening of fermented dairy products.