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Detection and characterization of a bacteriocin produced by Lactococcus lactis subsp. cremoris R isolated from radish
Author(s) -
Serkan Yıldırım,
; Johnson
Publication year - 1998
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1046/j.1472-765x.1998.00335.x
Subject(s) - lactococcus lactis , food spoilage , lactococcus , bacteria , biology , microbiology and biotechnology , bacteriocin , listeria , staphylococcus xylosus , food science , papain , pediococcus acidilactici , nisin , listeria monocytogenes , staphylococcus aureus , biochemistry , enzyme , lactic acid , staphylococcus , antimicrobial , genetics , lactobacillus plantarum
Bacteria isolated from radish were identified as Lactococcus lactis subsp. cremoris R and their bacteriocin was designated lactococcin R. Lactococcin R was sensitive to some proteolytic enzymes (proteinase‐K, pronase‐E, proteases, pepsin, α‐chymotrypsin) but was resistant to trypsin, papain, catalase, lysozyme and lipase, organic solvents, or heating at 90 °C for 15, 30 and 60 min, or 121 °C for 15 min. Lactococcin R remained active after storage at −20 and −70 °C for 3 months and after exposure to a pH of 2–9. The molecular weight of lactococcin R was about 2·5 kDa. Lactococcin R was active against many food‐borne pathogenic and food spoilage bacteria such as Clostridium, Staphylococcus, Listeria, Bacillus, Micrococcus, Enterococcus, Lactobacillus, Leuconostoc, Streptococcus and Pediococcus spp., but was not active against any Gram‐negative bacteria. Lactococcin R was produced during log phase and reached a maximum activity (1600 AU ml −1 ) at early stationary phase. The highest lactococcin R production was obtained in MRS broth with 0·5% glucose, at 6·5–7·0 initial pH values, 30 °C temperature and 18–24‐h incubation times. Lactococcin R adsorbed maximally to its heat‐killed producing cells at pH 6–7 (95%). Crude lactococcin R at 1280 AU ml −1 was bactericidal, reducing colony counts of Listeria monocytogenes by 99·98% in 3 h. Lactococcin R should be useful as a biopreservative to prevent growth of food‐borne pathogenic and food spoilage bacteria in ready‐to‐eat, dairy, meat, poultry and other food products. Lactococcin R differs from nisin in having a lower molecular weight, 2·5 kDa vs 3·4 kDa, and in being sensitive to pepsin and α‐chymotrypsin to which nisin is resistant.