Probiotic bacteria exhibited molecular changes, particularly on the cell surface, which are bound to impact on gene expression and function of the human intestine, according to findings published in The ISME Journal.
“These results identify the niche-specific adaptations of a dietary microorganism to the intestinal ecosystem and provide novel targets for molecular analysis of microbial–host interactions which affect human health,” wrote the researchers, led by Prof Michiel Kleerebezem from NIZO Food Research.
Talking to NutraIngredients, Prof Kleerebezem said that the study is unique because the samples examined came from humans. “Several people have studied this in animals, but our study shows that there is a specific human adaption of these bacteria that is not seen in mice,” he said.
There are major changes in cell surface properties, said Prof Kleerebezem, and the new study showed that the form of the probiotic perceived by the intestinal mucosa may not be the same as the form of the probiotic added to the food product. The bacteria adapt to the gastrointestinal conditions.
Prof Kleerebezem and his co-workers focussed their attention on changes to the established probiotic Lactobacillus plantarum 299v in the intestinal mucous membrane of five patients suffering from colon cancer. The patients were given bacteria drinks for eight days before an operation in which part of the intestine was removed. For control purposes one patient received a drink without lactic acid bacteria.
Using genetic analysis techniques called comparative transcriptome analysis, the researchers showed that a range of genes involved in the production and utilisation of proteins and sugars were induced.
Data showed that the bacterial response was dominated by the production of these proteins on the surface, and that these proteins were involved in the acquisition of carbohydrates for the cell.
“Cell surface proteins such as Lp_2940 for which the functional properties are currently unknown are among a growing repertoire of Lactobacillus cell products providing specific contributions in the mammalian gut, which are not related to host diet,” wrote the researchers.
“These proteins are prime targets for unraveling the mechanisms by which probiotic bacteria affect human health through targeted interactions with intestinal epithelial and immune cells in ways that encompass the integrated contributions of the gut microbiota and host diet on the human body,” they added.
The next stage in this research is to understand which molecules impact for a certain kind of response, said Prof Kleerebezem. “I think this is crucial to discriminate one probiotic product from another,” he said.
Source: The ISME journal
Published online ahead of print, doi: 10.1038/ismej.2010.61
“Convergence in probiotic Lactobacillus gut-adaptive responses in humans and mice”
Authors: M.L. Marco, M.C. de Vries, M. Wels, D. Molenaar, P. Mangell, S. Ahrne, W.M. de Vos, E. Vaughan, M. Kleerebezem