Polyphenol Blend–Lactobacillus Pairings Reveal Strain- and Time-Specific Growth Promotion for Synbiotic-Oriented Functional Foods

INTRODUCTION

The rational design of synbiotic-oriented foods requires identification of plant-derived substrates that selectively support specific beneficial microorganisms rather than producing a uniform response across strains. This study evaluated whether polyphenol-rich preparations from Elaeagnus multiflora ‘Sweet Scarlet’, Vitis vinifera ‘Solaris’, and Amelanchier alnifolia ‘Smoky’, used individually or as binary and ternary blends, differentially modulate the growth of selected Lactobacillus strains.

METHODS

Polyphenolic preparations were obtained from plant materials and characterized by UPLC-PDA-MS/MS with respect to major phenolic groups, including phenolic acids, anthocyanins, flavonols, and flavan-3-ols. Their effects were tested against Lactobacillus rhamnosus GG, L. helveticus, L. salivarius, and L. plantarum 299v. Cultures were incubated for 72 h, with bacterial abundance determined at 24, 48, and 72 h using optical density measurements converted to cell numbers with strain-specific calibration curves.

RESULTS

UPLC-PDA-MS/MS analysis confirmed marked compositional differences among the three botanical preparations, particularly in the relative contribution of phenolic acids, anthocyanins, flavonols, and flavan-3-ols. Thus, the bacterial-growth experiments compared not only different botanical sources but also chemically distinct polyphenol profiles. The response to supplementation was strongly strain- and time-dependent. The strongest effect was observed for L. rhamnosus GG: the ternary blend increased abundance to 11.68 log units after 48 h compared with 9.63 in the control, corresponding to an approximately 114-fold increase. L. helveticus responded most strongly during the early stage of cultivation, reaching 9.42 log units with a selected binary blend after 24 h versus 8.02 in the control, an approximately 25-fold difference. L. salivarius showed a distinct response pattern, with selected blends producing the greatest stimulation after 24 h; the best-performing formulation reached 10.85 compared with 9.92 log units in the control. In contrast, L. plantarum 299v showed its strongest response to a single botanical preparation, reaching 10.29 versus 9.20 log units after 72 h, equivalent to approximately a 12-fold increase. The lack of a common optimum across strains, despite exposure to the same set of preparations, indicates that the observed effects were associated with both botanical origin and polyphenol composition rather than simply with the use of more plant sources.

CONCLUSIONS

The results demonstrate that chemically distinct polyphenol profiles generate strain-specific and time-dependent responses in Lactobacillus. Multicomponent blends were particularly effective for L. rhamnosus GG and selected responses of L. helveticus and L. salivarius, whereas L. plantarum 299v favored an individual botanical preparation. These findings suggest that the design of synbiotic-oriented formulations should consider not only the botanical source or total polyphenol load, but also the qualitative and quantitative distribution of individual phenolic classes.

Funding: National Science Centre, Poland, grant No. 2020/39/D/NZ9/01810.