Title : Elucidating next-generation probiotic potential of lead enterococcus faecium strains through in vitro aggregation and adhesion profiling
Abstract:
The effectiveness and action potential of probiotics depend on their adhesion to the host tissue. The effective host interactions rely heavily on their ability to aggregate and adhere to host tissues, thereby supporting mucosal colonization, immune modulation, and competitive exclusion of pathogens. In the present study, six locally isolated Enterococcus faecium strains were evaluated for their aggregation behavior and adhesion potential following the established protocol and developing simulated gastrointestinal conditions. All selected strains demonstrated high-level auto-aggregation potential (?75%) after 1 h of incubation. The highest potential was shown by E. faecium TWCST1 and E. faecium Se142 (82%), followed by E. faecium NF (80%). The visual auto-aggregation was assessed visually after 24 hrs of incubation, revealing that all strains exhibited a score of +3, indicating moderate aggregation with low turbidity, whereas E. faecium NF showed a score of +4, reflecting higher turbidity and stronger aggregation. This auto-aggregation likely facilitates initial colonization within the gastrointestinal tract and increases competitive exclusion of enteric pathogens. Co-aggregation results revealed that the selected strains show variable percentages against different indicator strains and range from −36 to 46%. After 24 h of incubation, high co-aggregation was observed between E. faecium NF and L. monocytogenes and E. faecium F25 with Proteus mirabilis (46%), followed by E. faecium TWCST1 and E. faecium M30 with Lactobacillus spp. (39%). Beyond self-aggregation, adhesion to host molecules was assessed through binding assays using fibrinogen and mucin, critical components of mucosal surfaces. All strains exhibited measurable mucin adhesion, underscoring their potential to interact with the mucus layer lining the gut, an essential step for stable colonization. The highest mucin-binding potential was observed in E. faecium TWCST1, followed by E. faecium Se142, whereas E. faecium NF and E. faecium F25 showed comparatively lower adhesion. The fibrinogen binding capacity varied. The highest was observed in E. faecium M30 (27.21%), followed by E. faecium NF (22.75%). In contrast, E. faecium Se142 and E. faecium F25 exhibited negative binding values, measuring -10.75% and -25.89%, respectively. These adhesion profiles suggest that the selected E. faecium strains possess diverse surface properties that contribute to host interaction. The combined aggregation and adhesion traits observed indicate a robust ability to remain associated with host tissues, enhancing probiotic performance. These functional properties, coupled with stress tolerance and safety traits, highlight the suitability of these E. faecium strains as promising next-generation probiotic candidates for advanced probiotic formulations aimed at improved host interaction and health benefits.
