Isolation and assessment of novel exopolysaccharide-producing Weissella confusa ABRIIFBI-96 isolated from an Iranian homemade dairy fermented food “Tof” as a main starter culture for probiotic fermented milk

This study focused on evaluating lactic acid bacteria (LAB) isolates for their probiotic characteristics and safety, as well as potential as a primary starter culture in probiotic fermented milk production. Ten LAB isolates underwent in vitro testing to assess their probiotic potential. While these isolates were susceptible to ten antibiotics, none of them showed sensitivity to vancomycin. Particularly, the isolates, especially ABRIIFBI-96, demonstrated substantial resistance to bile salts (80.48 ± 0.37%) and low pH (82.05 ± 0.1%), along with strong adhesion ability to Caco-2 cells (22.59 ± 0.36%). Notably, isolate ABRIIFBI-96 exhibited impressive auto-aggregation and co-aggregation capabilities (33.45 ± 0.36 and 28.66 ± 0.4, respectively) and had the highest cholesterol-reducing capability (35.63 ± 0.64%) without any hemolytic activity. Furthermore, isolate ABRIIFBI-96 demonstrated robust bile salt hydrolase activity with both glycolic and taurocholic tested bile salts. It exhibited inhibitory activity against all tested pathogens, establishing its significant probiotic potential and suitability for incorporation into functional food formulations. The results were highly promising, as the use of isolate ABRIIFBI-96 reduced fermentation time to just 10 h, and the microbial count in the final products ensured their probiotic activity even after 28 days of storage (with a reduction of 0.899 log CFU mL−1). •This is the first report about use of Weissella as a starter culture.•Weissella confusa ABRIIFBI-90 was successfully employed as primary starters in fermented milk production.•W. confusa ABRIIFBI-90 reduced cholesterol levels in fermented products and produced exopolysaccharides.