Fructobacillus fructosus isolated from palm wine: functional screening and safety evaluation as a potential probiotic

Fructobacillus fructosus, a specialized fructophilic lactic acid bacterium from traditional fermented ecosystems, remains largely unexplored for its functional probiotic properties. This study established a robust, experimentally validated in vitro baseline of the probiotic potential and safety profile of the Fructobacillus fructosus strain MRS-3 isolated from traditional palm wine. The taxonomic identification was confirmed by 16 S rRNA gene sequencing and phylogenetic analysis. In vitro screening assays were used to evaluate the gastrointestinal survivability (acid/bile tolerance) and cell surface traits (autoaggregation, hydrophobicity, and Caco-2 cell adhesion) of the isolate. Baseline biological safety was quantitatively determined using minimum inhibitory concentration (MIC) values against reference breakpoints and a hemolysis assay. Strain MRS-3 was confirmed as Fructobacillus fructosus (GenBank: PV123975.1) by 16 S rRNA gene sequencing and exhibited growth across a broad range of pH, salt concentrations, and temperatures. It demonstrated tolerance to acidic and bile salt conditions, with viable counts ranging from 5.3 to 5.9 and 5.4 to 5.98 log CFU/mL, respectively. The strain showed high auto-aggregation (94.8%) and cell-surface hydrophobicity toward xylene (90%), toluene (90.9%), and hexane (76%), together with co-aggregation with selected indicator strains and measurable adhesion to Caco-2 intestinal epithelial cells. No hemolytic activity was observed, and inhibition zones were observed in the antibiotic susceptibility study under the experimental conditions spanning 18 to 27 mm. The results obtained strongly support the potential of Fructobacillus fructosus MRS-3 isolated from palm wine as a safe and functional probiotic candidate. This study provides a critical empirical baseline for the genus, demonstrating that its phenotypic traits merit future targeted in vivo validation.