Survival of probiotic bacteria in the presence of food grade nanoparticles from chocolates: an in vitro and in vivo study

The use of probiotics to treat gastrointestinal diseases such as diarrhea especially in children is becoming increasingly popular. Besides, the use of nanomaterials in food products is increasing rapidly especially in candies and chocolates. How these nanomaterials influence probiotic bacteria and their activity remains unexplored. Therefore, nanomaterials from commercial chocolate were purified and characterized by using SEM–EDS and XRD. The tested chocolate contained nano-TiO 2 with an average size of ~ 40 nm. The influence of the extracted TiO 2 on a commercial probiotic formulation usually used to treat diarrhea in children was studied. The probiotic formulation contained Bacillus coagulans , Enterococcus faecalis , and Enterococcus faecium as evident from 16S rRNA gene sequences and polyphasic characterization. Isolated bacteria exhibited known probiotic activities like biofilm formation, acid production, growth at 6% salt, and antibiotic resistance. TiO 2 from chocolates inhibited the growth and activity of the probiotic formulation over a concentration range of 125–500μg/ml in vitro. Based on results, it is estimated that 20 g of such chocolate contains enough TiO 2 to disturb the gut microbial community of children aged 2–8 years with a stomach capacity of ~ 0.5–0.9 l. The in vivo study on white albino mice shows the same response but with a higher dose. The results obtained by plate counts, MTT assay, live/dead staining, and qPCR suggest that TiO 2 from chocolates inhibits the growth and viability of probiotic bacteria in mice gut even at a concentration of 50–100 μg/day/mice. Therefore, TiO 2 in chocolate discourages survival of probiotic bacteria in the human gut.