Study on Protease of Dairy Bacteria

Part II. Action of Intracellular Protease of Lactic Acid Bacteria on Paracasein

Abstract

Experiments were carried out to elucidate how paracasein was hydrolyzed by the intra-cellular protease of lactic acid bacteria (IPLB) prepared from S. cremoris and other three kinds of lactic acid bacteria. Various para-caseins prepared by exposing casein for variouss time were used as substrates.
These results show that paracaseins prepared by releasing of non casein type nitrogen (NCN) of 3_??_7% from native casein were hydrolyzed by IPLB more hardly than those prepared by releasing of 7% NCN or above-This phenomenon was not found in the ex-periment which was carried out by a neutrar. protease.
Results of DEAE-cellulose column chroma-tography or agar-gel or starch-gel electrophore-sis showed that rennin or IPLB of S. cremoris hydrolyzed some parts of α_s-casein during the early stage of hydrolysis. During that stage-β-casein was also hydrolyzed by IPLB of S. cremoris.