title: Tailoring the probiotic potential of non-starter Lactobacillus strains from ripened Parmigiano Reggiano cheese by in vitro screening and principal component analysis.
abstract: Non-starter lactic acid bacteria (NSLAB) inhabiting fermented food have been recently revised as source of probiotic strains. Here, we in vitro assessed the potential probiotic aptitude of a de-replicated set of NSLAB previously isolated from long ripened Parmigiano Reggiano cheeses (22 Lactobacillus rhamnosus, 18 Lactobacillus paracasei, 3 Lactobacillus casei, 2 Lactobacillus harbinensis, and 2 Lactobacillus fermentum). Most strains showed moderate to good resistance to biological barriers, including bile salts, lysozyme, and simulated gastric and pancreatic juices. Antimicrobial susceptibility tests against seven antimicrobials belonging to different categories showed that most strains are susceptible towards all the antibiotics, with the exception of vancomycin and streptomycin. The strains lost the streptomycin resistance when assayed on agar medium containing 0.5% bile salts, suggesting that detergent-like properties of cholic acids increase membrane permeability and mediate streptomycin susceptibility. No isolate showed bile salt hydrolase (BSH) activities, supporting that bile salts resistance and BSH activity are unpaired traits. Finally, NSLAB strains had moderate to high auto-aggregative and hydrophobic phenotypes, whereas two subsets of 22 and 8 strains co-aggregated with Escherichia coli and Salmonella enterica s. typhimurium, respectively. A multivariate analysis was effective to segregate one L. casei and two L. rhamnosus strains showing physiological characteristics compatible with probiotic properties.
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, via Amendola 2, Besta Building, 42122 Reggio Emilia, Italy. Electronic address: lisa.solieri@unimore.it.
authors.forename: Lisa
authors.initials: L
authors.lastname: Solieri
authors.forename: Aldo
authors.initials: A
authors.lastname: Bianchi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mottolese
authors.forename: Federico
authors.initials: F
authors.lastname: Lemmetti
authors.forename: Paolo
authors.initials: P
authors.lastname: Giudici
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002611:Cheese / Q000382:microbiology*; D007778:Lactobacillus / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D025341:Principal Component Analysis; D019936:Probiotics / Q000145:classification / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antibiotic susceptibility; Gastro-intestinal resistance; Lactobacillus; Non-starter lactic acid bacteria; Parmigiano Reggiano cheese; Principal component analysis; Probiotic