Kefiran fermentation by human faecal microbiota: Organic acids production and in vitro biological activity

Abstract

The present study aimed to evaluate the fermentation of the glucogalactan kefiran by human intestinal microbiota, and to assess the biological effect triggered by the produced metabolites (butyrate and others). For this purpose, an in vitro fermentation model with faeces belonging to ten (10) children between 4 months to 3 years-old was used. Short-chain fatty acids (SCFA) and lactic acid production was evaluated by high performance liquid chromatography (HPLC). Biological activity of the produced metabolites was assessed on the proliferation and viability of a high invasive colorectal cancer cell line (HT-29). It was found that kefiran was able to be fermented by microorganisms present in all the faecal samples included in the study. Kefiran fermentation triggered to acidification of the culture medium and the production of organic acids. Acetic acid was mainly produced after 24 h of fermentation, while propionic acid was mainly found at 48 h. In some cases, butyric acid was significantly increased after 48 h of fermentation. Biological activity of a selected sample with high content of butyric acid was evaluated on HT-29 tumoral cell line. It was found a diminishment of cell proliferation and an induction of cell death processes. The presented results demonstrate that kefiran can be fermented by human intestinal microbiota and that the consequently produced metabolites could elicit a beneficial effect on health.