Induction of gut Lactobacillus reuteri in normal ICR mice by oral administration of L. plantarum AN1

Abstract

To clarify the existence of indigenous intestinal gut bacteria sensitive to orally administered probiotic strains of lactic acid bacteria, the effects of live and heat-killed Lactobacillus plantarum AN1 cells, administered to normal ICR mice via drinking water were observed. Amplicon sequencing of the 16S rDNA (V4) of caecal contents revealed that the live AN1 cells increased the abundance of an indigenous sensitive gut bacterium (SGB) Lactobacillus reuteri. From faecal samples, five typical dominant colonies were detected on BL agar. Among the typical colonies, smooth brown colonies were detected only in mice fed live AN1 cells, and small brown colonies with a black centre were detected in mice fed live and heat-killed AN1 cells. These two colony types were determined to be L. plantarum and L. reuteri, respectively. Three other typical dominant colonies were detected in all mouse groups, and were determined to be Lactobacillus intestinalis, Lactobacillus gasseri, and L. reuteri, respectively. These results suggest that non-dominant L. reuteri is an L. plantarum-SGB in ICR mice. Practical applications The non-dominant L. reuteri is an L. plantarum-SGB in ICR mice, and it is possible to demonstrate functionality with orally administered probiotics. Isolation and application of human or livestock SGB is considered promising for the development of new functional foods.