Probiotic properties and anti-helicobacter pylori activity of lactic acid bacteria from plant and fermented food products

Abstract

Two hundred and thirty-eight strains of lactic acid bacteria (LAB) isolated from several plant-materials and fermented food products collected in Thailand were screening for antibacterial activity. Fifty-three strains which exhibited antimicrobial activity against Helicobacter pylori clinical strains, were selected and identified based on the phenotypic, chemotaxonomic characteristics and 16S rRNA gene sequence analysis. They were identified as Lactobacillus (Lb.) plantarum subsp. plantarum (3 strains), Lb. pentosus (10 starins), Pediococcus (P.) pentosaceus (2 strains), Lb. paracasei subsp. tolerans (1 strain), Lb. fermentum (5 strains), Enterococcus (En.) faecium (2 strains), En. casseliflavus (1 strain), Lactococcus (Lc.) garvieae subsp. garvieae (1 strain), Lc. lactis subsp. lactis (3 strains), Leuconostoc (Ln.) lactis (2 strains), Ln. citreum (2 strains), Ln. pseudomesenteroides (2 strains), Weissella (W.) paramesenteroides (1 strain), W. cibaria (6 strains) and W. confusa (11 strains). Strain Ru20-1T isolated from West-Indian jasmine (Ixora coccinea L.) was closely related to Lb. lindneri LMG 14528T (96.8 %) and Lb. sanfranciscensis NRIC 1548T (92.0 %) based on 16S rRNA gene sequence and pheS gene sequence similarity, respectively. Phylogenetic analysis indicated that strain Ru20-1T was clearly separated from related species of the genus Lactobacillus. On the basis of polyphasic taxonomy, strain Ru20-1T was proposed as Lactobacillus ixorae sp. nov.

The adherence abilities assay of selected strains on AGS cell lines, Ln. pseudomesenteroides strain BGM-S4 showed the highest adhesion ability (20.4%) followed by Ln. pseudomesenteroides strain FM-S16 (12.9%). While the other strains exhibited the adherence lower than 5%. Lb. fermentum P43-01 exhibited antimicrobial activity against H. pylori MS83 and BK364, was selected for evaluate the acid and bile tolerance. This strain had constant viability at pH 3 (7.6 log10 cfu/ml) and the numbers were approximately decreased 2 log cycles after incubation at pH 2 for 3 h. After exposure to bile acids for 6 h at 0.3% and 0.5%, a strain was slightly increased 1.5 and 1 log cycles, respectively.

The treatment of proteinaceous compounds, bacteriocin-like substances (BLS), produced by strain FM-S16 and P43-01 using protease, revealed that BLS of strain FM-S16 was sensitive to proteinase K while the BLS of strain P43-01 was sensitive to a-chymotrypsin and pepsin. These indicated that BLS of the selected strains might be the significant mechanism that exerted the inhibition on H. pylori. According to the highest anti-H. pylori activity of strain FM-S16, it was chosen for partial purification through the hydrophobic interaction, cation-exchange and reverse-phase high performance liquid chromatography with 380-fold of purity. The molecular mass of partially purified bacteriocin was in the range of 1094-1316 Da.