Peptidases of Lactobacillus casei and L. plantarum

Abstract

Fractionation of cell-free extracts of Lactobacillus casei NCDO 151 (grown in Man's et al. (1960) broth) by polyacrylamide disc electrophoresis showed the presence of 4 constitutive peptidases. The enzymes appear to be a tripeptidase with a narrow substrate specificity, two true dipeptidases with identical broad-specificity, and a probable carboxypeptidase with broad-specificity. A probable amino peptidase could also be isolated from the cell-free extract by density gradient electrofocusing. Growth of the organism in skim milk resulted in the formation of two inducible dipeptidases. Examination of 5 other strains of L. casei for the presence of the two constitutive dipeptidases and the carboxypeptidase confirmed the results obtained for the species. Some strains, however, had one more peptidase. The peptidases of the strains differed relatively in the activity and substrate specificity from strain to strain. On polyacrylamide gel, the peptidase activity of L. plantarum appeared as one band only, probably of a carboxypeptidase.

The Sourdough Microflora. Cellular Localization and Characterization of Proteolytic Enzymes in Lactic Acid Bacteria

“…Several differences among species and subcellular location of peptidases have been found. Iminopeptidase activity was only detected in L. bulgaricus, L. helveticus, L. casei and L. plantarum (33), and carboxypeptidase was only detected in L. casei (34,35) and Bifidobacterium strains (36). These two activities appeared to be not common in sourdough Lactobacillus: only L. brevis subsp.…”

Purification and characterization of the X-prolyl-dipeptidyl aminopeptidase (PepX) from Streptococcus macedonicus and cloning of the pepX gene

“…They have limited abilities to synthesize amino acids, which are essential for their growth, and milk contains insufficient amounts of free amino acids and low molecular mass peptides to sustain growth [1,25,50]. Although they are considered as weak proteolytic bacteria compared with other groups of microorganisms, it has been shown that lactic acid bacteria possess a complex proteolytic system capable of hydrolyzing milk proteins to peptides and amino acids [23,37,41,43,45].…”

Cloning and nucleotide sequence analysis of pepV, a carnosinase gene from Lactobacillus delbrueckii subsp. lactis DSM 7290, and partial characterization of the enzyme

“…Due to the rather low content of free essential amino acids in milk they are dependent on their proteolytic abilities to degrade milk casein. Lactobacilli possess a complex proteolytic system composed of proteinases and a variety of peptidases (Abo-Elnaga & Plapp, 1987;Law & Kolstadt, 1983;Thomas & Pritchard, 1987), which act in a cascade to hydrolyse casein to small transportable peptides and amino acids. The quality of dairy products The GenBanWEMBUDDBJ accession number for the nucleotide sequence reported in this paper is 231377.…”