Conceptualizing 'food parcel for colon microbes' designed for delivering to human colon which assists the growth of the probiotics there: An exploratory in vitro study with Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis BB-12

Long-term colonization of desired probiotic bacteria in human colon environment is still tough to achieve for now. In this exploratory in vitro study, we demonstrated the difficulties in proliferation of Lactobacillus rhamnosus GG (LGG) and Bifidobacterium animalis subsp. lactis BB-12 (BB-12) in the substrate of post intestinal digestion products (PIPD) made from skimmed milk. Results of poor growth in the digesta (1.54 log N/N0 for LGG, while-0.54 log N/N0 for BB-12) provided evidence on mechanisms of low survival of the two strains in simulated colon environment. Adscititious glucose significantly promoted viable counts of LGG and BB-12 in PIPD, thus is promising to serve as possible tailor made 'food' for colon fermentation of probiotics. Based on the results, we propose a new concept that may be called as 'food parcel for colon microbes', which can be delivered to simulated human colon environment and assist the growth of the probiotics already existing there. In the current study, we selected the 'glucose parcel' as an initial example. The 'glucose parcel' can be released into colon based on its pH-dependent dissolvability. With the direct delivery of glucose, the log (N/N0) values of LGG in single-species and mixed-species cultivations reached 2.10 and 2.24, respectively. The log (N/N0) value of BB-12 was 1.04 in single-species, and 1.30 in mixed-species cultivation. 'Food parcel for colon microbes' will be hopeful in promoting colonic probiotic fermentation and providing an innovative strategy for achieving long-term colonization of the probiotics and regulating the gut microbiota in human colon.

Automated summary

Long-term colonization of desired probiotic bacteria in the human colon is difficult to achieve. This study explored the challenges in the growth of Lactobacillus rhamnosus GG (LGG) and Bifidobacterium animalis subsp. lactis BB-12 (BB-12) in a simulated colon environment. The addition of glucose significantly promoted the growth of LGG and BB-12, suggesting it could serve as a potential "food" for colon fermentation of probiotics. The concept of a "food parcel for colon microbes" was proposed, which may be a promising strategy for promoting probiotic colonization and regulating gut microbiota in the colon.