Affiliation:
1. New Zealand Dairy Research Institute, Department of Microbiology and Genetics, Massey University, Palmerston North, New Zealand
Abstract
Variants of
Streptococcus lactis
that produce lactic acid slowly in milk were isolated by inducing plasmid loss in the wild type at 39 to 40 C. Such strains had lost most of their surface-bound proteinase activity and were designated
prt
-
. The specific proteinase activities of
S. lactis
C10
prt
+
whole cells and solubilized cell walls were 7 and 18 times, respectively, those of the
prt
-
strain, but spheroplast lysates of
prt
+
and
prt
-
strains contained similar proteinase activity.
S. lactis
H1 showed a similar relative distribution of activity between
prt
+
and
prt
-
cellular fractions, although the overall level was lower. The limited growth in milk, characteristic of
prt
-
strains, can be explained in terms of their low surface-bound proteinase activity.
Publisher
American Society for Microbiology
Subject
General Pharmacology, Toxicology and Pharmaceutics,General Immunology and Microbiology,General Biochemistry, Genetics and Molecular Biology,General Medicine
Cited by
8 articles.
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