title: Isolation and characterization of proteinase- and aminopeptidase-deficient mutants of Lactobacillus casei subsp. casei IFPL 731.
abstract: Proteinase-deficient (Prt-) and aminopeptidase-deficient (Amp-) variants of Lactobacillus casei subsp. casei IFPL 731 were isolated and characterized. The Prt- mutant was isolated from strains that developed poorly on glucose milk agar. The Amp- mutant was isolated on the basis of its inability to hydrolyse L-leucine-beta-naphtylamide. The Prt- variant developed poorly, while in milk the Amp- variant grew at about the same rate as the parental strain. The characterization of aminopeptidase activity in more detail showed that at least two enzymes are involved The results of the present study suggest that the proteolytic system of Lactobacillus casei is subjected to a regulatory system.
authors.affiliation: Instituto del Frío (CSIC), Ciudad Universitaria, Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Fernández de Palencia
authors.forename: M C
authors.initials: MC
authors.lastname: Martín-Hernández
authors.forename: H M
authors.initials: HM
authors.lastname: Joosten
authors.forename: C
authors.initials: C
authors.lastname: Peláez
mesh_terms: D000626:Aminopeptidases / Q000172:deficiency / Q000235:genetics*; D000818:Animals; D002455:Cell Division; D002611:Cheese / Q000382:microbiology*; D003470:Culture Media; D010450:Endopeptidases / Q000172:deficiency / Q000235:genetics*; D007700:Kinetics; D007780:Lacticaseibacillus casei / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D008892:Milk; D016296:Mutagenesis; D009154:Mutation
chemical_list: D003470:Culture Media; D010450:Endopeptidases; D000626:Aminopeptidases