Evaluation of the counts and survival of the probiotic strains contained in the formulation in vitro

Graphical abstract Abstract Objective Significant scientific and industrial research on probiotic strains is influencing the growing size of the market. This underlines the ongoing need for an accurate declaration of identification, with proven safety and functionality of the incorporated strains. Methods The research was designed to address two key issues, first, to assess the viability of strains of commercially available probiotic formulation, and second, to test the survival of probiotics in the gastrointestinal milieu in vitro. Therefore, we sought to validate the live cell counts and bacterial strains in probiotic products and compare the values with those declared on labels. The viable plate count was used to determine the number of viable microbes present in the oral probiotic suspension. To assess the capacity of the strains contained in the probiotic product to survive the extreme environment of the gastrointestinal tract (GIT), an in vitro approach involving the simulated gastric and intestinal fluids was applied. As the tested product is intended for newborns and infants, we simulated infant GIT conditions. Results The analysis revealed that probiotic product samples matched the label data regarding viable cell counts and contained probiotic species. Microbiological analysis and next-generation sequencing (NGS) long read excluded the presence of contaminating non-probiotic bacteria in the probiotic product. Conclusions The probiotic strains, contained in the formulation, effectively survived simulated intestinal conditions in vitro , fulfilling one of the first requirements in the quality assurance assessment of probiotics. Significance statement These findings support the importance of probiotics as a microbiota-modulating strategy.