Abstract
We characterized the antibacterial activity of Lactobacillus curvatus strain Y108 isolated from the traditional Japanese pickle Nozawana-zuke, and partially identified the antibacterial agent produced by the strain. The Y108 strain exhibited antibacterial activity against L. curvatus JCM1096, Listeria monocytogenes JCM7671, Staphylococcus aureus subsp. aureus JCM20624, and Serratia marcescens JCM20012.The antibacterial activity was abolished upon treatment with several proteases and lipase but not catalase, and it was moderately stable against heat treatment for 2 h at 100°C. The Y108 strain showed higher antibacterial activity when grown at 20°C than at 30°C, which is its optimal growth temperature. SDSPAGE analysis of the purified culture supernatant revealed the presence of two antibacterial peptide agents, F3-I and F3-II, with net molecular weights of 5.5 and 4.5 kDa, respectively. The N-terminal amino acid sequences of F3-I and F3-II were homologous to those of lactocin 705α and 705β, respectively. However, molecular masses and individual antibacterial activities of the two peptides were considerably different from those reported for lactocin 705.
