Characterization of pentocin TV35b, a bacteriocin-like peptide isolated from Lactobacillus pentosus with a fungistatic effect on Candida albicans

Lactobacillus pentosus TV35b, isolated from the posterior fornix secretions of the vagina of a prenatal patient, produced a bacteriocin-like peptide ( pentocin TV35b), which is inhibitory to Clostridium sporogenes, Cl. tyrobut yricum, Lact. curvatus, Lact. fermentum, Lact. sake, Listeria innocua, Prop ionibacterium acidipropionici, Propionibacterium sp. and Candida albicans. The mechanism of activity of pentocin TV35b is bactericidal, as shown by a decrease in the viable cell numbers of Lact. sake from approximately 4 x 10 (8) to less than 10 cfu ml(-1) over a period of 4 h. Pentocin TV35b added t o the growth medium of C. albicans stimulated the formation of pseudohyphae during the first 36 h, followed by a slight repression in cell growth. Pro duction of pentocin TV35b was at its maximum towards the end of the logarit hmic growth phase of strain TV35b. The peptide was purified by ammonium sul phate precipitation, followed by SP-Sepharose cation exchange chromatograph y. The molecular size of pentocin TV35b was estimated to be between 2.35 an d 3.4 kDa, according to tricine-SDS PAGE. However, results obtained by elec trospray ionization mass spectroscopy indicated that the peptide is 3930.2 Da in size. Amino acid analysis performed by using the Pico-Tag (R) method and a Nova-Pak C-18 HPLC column indicated that pentocin TV35b consists of 3 3 amino acids with a total mass of 3929.63 Da. Pentocin TV35b is inactivate d when treated with papain and Proteinase K, but remains active after incub ation at pH 1-10 for 2 h at 25 degrees C, and when heat-treated for 30 min at 100 degrees C.