Probiotic potential of lactic acid bacteria from traditional fermented dairy and meat products : assessment by 𝘪𝘯 𝘷𝘪𝘵𝘳𝘰 tests and molecular characterization

Abstract

The aim of the present study was to evaluate the probiotic potential of lactic acid bacteria (LAB) isolated from Greek traditional fermented products. A series of in vitro tests that included survival in simulated gastrointestinal conditions (resistance to low pH, bile salts resistance and bile salts hydrolysis) and safety assessment (resistance to antibiotics, haemolytic and antimicrobial activity) were performed to select potential probiotic candidates, while Lactobacillus rhamnosus GG and Lactobacillus casei Shirota were used as reference strains. Initially, a total of 255 isolates of LAB have been recovered and screened for their survival in simulated gastrointestinal tract conditions and 133 isolates that exhibited moderate or good behavior in these tests were subsequently differentiated and characterized at species level with molecular tools. Pulsed Field Gel Electrophoresis was applied for strain differentiation, while species differentiation was based on restriction analysis of the amplified 16S rRNA gene. Specific multiplex PCR assay targeting the recA genes was applied to resolve the species level of the isolates, belonged to Lb. plantarum group. From the 133 isolates, 47 different strains were recovered and were assigned to Lactobacillus sakei (14), Lactobacillus curvatus (4), Leuconostoc mesenteroides (4), Lactococcus lactis (4), Lactobacillus casei group (1), Lactobacillus brevis (1), Lb. plantarum (10), Lb. pentosus (7) and Lb. paraplantarum (2). The identified strains with good behavior to the gastrointestinal tract tests were selected and further evaluated for their safety aspect. In conclusion, 19 out of the 47 identified strains were assessed as well-behaved, under simulated gastrointestinal conditions and also considered as safe, possessing thus desirable in vitro probiotic properties similar or better to that of the reference strains. These strains may be considered as good candidates for further investigation at in vivo and in situ studies to assess their potential health benefits and their performance as novel probiotic starters or adjunct cultures.