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KMID : 0380619890210010086
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Korean Journal of Food Science and Technology
1989 Volume.21 No. 1 p.86 ~ p.91
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Effect of N - sources and NaCl Concentrations in Media on the Intra - and Extracellular Proteinase Activities of Streptococcus cremoris ML4 and Streptococcus lactis ML8
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Abstract
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To investigate the effect of NaCl concentration and nitrogen sources in the medium for the Streptococci on the intra- and extracellular proteinase(ICP and ECP) which have been known as one of the major causes for the bitter peptide formation, Streptococcus lactic ML_8 and Streptococcus cremoris ML₄ strains were incubated at 0-4% NaCl in the medium and Na-caseinate as a nitrogen source 0-100%, and the cell growth, ICP and ECP activities were analyzed. As the concentration of the NaCl in the medium increased, the growth and ECP activity decreased but the ICP activity/10^(10) cells increased on the contrary. This implied that the NaCl in the medium affects oply the ECP which is associated mainly to the cell wall and cell membrane but not the ICP activity. When the content of the caseinate instead of other low molecular nitrogen sources were increased in the medium, the cell growth was lowered while the ECP activities increased probably by induction of proteinase production.
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