In vitro Probiotic Characterization of Lactic Acid Bacteria Isolated from the Phylloplane of Selected Edible and Culinary Plants: Multivariate Trait Profiling and Composite Ranking of Candidate Strains

Abstract Lactic acid bacteria (LAB) on leaves eaten raw are ingested routinely, yet the phylloplane is almost unexamined as a source of probiotic candidates and the few described strains were ranked without testable criteria. Fifteen LAB were isolated from the phylloplane of eight edible and culinary plants, and five morphologically distinct isolates (LA, LAB-3, LAB-5, LAB-10, LAB-15) were evaluated in vitro for acid, bile, NaCl, phenol and temperature tolerance, haemolysis, antibiotic susceptibility, auto-aggregation and hydrophobicity. The trait matrix was analysed by principal component analysis, clustering, dose-normalised indices, composite ranking under three fixed and 10,000 random weightings, and a static two-stage transit model. All isolates were γ-haemolytic. Isolate LA, provisionally referred to Lactobacillus on phenotypic grounds, and LAB-15 retained 73–75% of reference growth at pH 2.0 and were not inhibited by 2.0% bile; LA showed the highest hydrophobicity (72%) and auto-aggregation (42%), with LAB-10 (60%) and LAB-15 (57%) also above the 50% threshold. All isolates grew at 6% NaCl, whereas 0.4% phenol reduced optical density by 50–84%. The first principal component captured 84.7% of variance, exceeding a permutation null (95th percentile 68.7%). LA ranked first and LAB-15 second under every fixed scheme, in 86–95% of random weightings and after leave-one-out re-analysis; modelled transit survival was highest for LAB-15 (79.0%) and LA (68.4%). LA and LAB-10 were resistant to ampicillin, chloramphenicol and azithromycin, a non-intrinsic phenotype requiring MIC and resistance-gene analysis before either isolate is advanced. The study delivers a weighting-robust shortlist of phylloplane LAB and a transferable ranking framework; molecular identification, safety and adhesion assays and in vivo evaluation remain prerequisites for any probiotic claim.