Prospecting and characterization of potential probiotic lactobacilli from animal gut and food sources

Indigenous Lactobacillus species from African environments remain insufficiently characterised, despite their potential to serve as locally adapted, cost-effective probiotic candidates. This study explored plant- and poultry-derived lactobacilli to identify strains with functional traits relevant to gastrointestinal survival, host interaction, and food-related applications. Eighteen isolates recovered from chicken gut, tomatoes, cucumbers, and bananas were identified by 16S rRNA sequencing and assessed in vitro for acid and bile tolerance, bile-salt hydrolase (BSH) activity, exopolysaccharide (EPS) production, cholesterol assimilation, antioxidant capacity, antimicrobial effects, auto-aggregation, hydrophobicity, adhesion to Caco-2 cells, and safety indicators, including haemolysis, DNase activity, and antibiotic susceptibility. The isolates exhibited pronounced strain-specific variation, with several functional traits occurring in coordinated patterns. Strong acid and bile tolerance frequently aligned with BSH activity, while EPS production correlated with enhanced auto-aggregation. Two tomato-derived Lactiplantibacillus plantarum strains (To3a and To3d) consistently demonstrated the most favourable combination of survival, functional, and safety attributes, including high acid/bile tolerance, notable antioxidant and antimicrobial activity, and strong adhesion to Caco-2 cells. All isolates were non-haemolytic and DNase-negative, and most remained susceptible to clinically relevant antibiotics. Locally sourced L. plantarum strains showed multiple complementary probiotic traits, underscoring their potential as regionally adapted candidates for food or microbial intervention applications. However, genomic characterisation and in vivo validation are required to confirm safety, exclude transferable resistance determinants, and substantiate probiotic efficacy.