To investigate the effects of probiotics, lactitol of different concentrations, and their combination on intestinal microbiota in mice.

Fifty C57BL/6J mice were divided into blank control group, probiotics group, lactitol of standard concentration group, lactitol of high concentration group, and combination of probiotics and lactitol group, 10 mice in each group, with no intervention, gavaged with 1×10⁹ colony-forming units(CFU)/d probiotics, with lactitol of standard concentration (6.6 g·kg^-1·d^-1), with lactitol of high concentration (10.0 g·kg^-1·d^-1), with probiotics (5×10⁸ CFU/d) and lactitol (3.3 g·kg^-1·d^-1) for two weeks, respectively. The feces before gavage and one week and two weeks after gavage were collected. And intestinal mucosa samples were also collected at two weeks after gavage for 16S rRNA sequencing. Alpha diversity analysis, principal component analysis (PCA) and taxonomy were used for analysis of the changes of microbiota.

The results of alpha diversity analysis showed there was no statistically significant difference in feces between before gavage and at one week after gavage (P=0.552, 0.062). The results of alpha diversity analysis and PCA indicated that there was no statistically significant difference in intestinal microbiota between lactitol of standard concentration group and lactitol of high concentration group (P=0.270 and 0.085). One week and two weeks after gavage, compared lactitol of standard concentration group and lactitol of high concentration group with blank control group and probiotics group, Akkermansia in feces both increased (one week after gavage, 0.114 3 vs. 0.003 9 and 0.013 1, 0.071 3 vs. 0.003 9 and 0.013 1; P<0.01, P=0.001 and P=0.001, 0.005; two weeks after gavage, which was 0.094 0 vs. 0.030 5 and 0.018 9, 0.142 4 vs. 0.030 5 and 0.018 9; P=0.044, 0.016 and 0.001, <0.01). Compared combination of probiotics and lactitol group with lactitol of standard concentration group and high concentration group, Bacteroides in feces increased (one week after gavage, 0.115 9 vs. 0.037 5 and 0.041 6, P=0.013 and 0.015; two weeks after gavage, 0.058 0 vs. 0.023 2 and 0.014 4, P=0.047 and 0.009). The increase of Lachnospiraceae appeared earlier in combination of probiotics and lactitol group (at one week after gavage). Two weeks after gavage, compared with that of blank control group, lactitol of standard concentration group and high concentration group, Lachnospiraceae in feces of probiotics group increased (all P<0.05). Compared with that of probiotics group, Akkermansia of mucosa in lactitol of standard concentration group increased (0.018 0 vs. 0.001 8, P=0.012). Akkermansia of mucosa in lactitol of high concentration group also increased compared with that of blank control group and probiotics group (0.037 0 vs. 0.010 0 and 0.001 8, P=0.002, <0.01). Comparing combination of probiotics and lactitol group with blank control group, lactitol of standard concentration group and lactitol of high concentration group, and comparing probiotics group with lactitol of high concentration group, Mucispirillum in mucosa all increased (0.040 0 vs. 0.014 8, 0.013 7 and 0.009 9, 0.019 6 vs. 0.009 9; P=0.041, 0.040, 0.018 and 0.011).

Supplementary probiotics, lactitol and combination of them all have obvious regulative role in mucosal flora of mice. Exogenous probiotics can not easily colonized in the intestine. Lactitol can obviously promote the proliferation of Akkermansia in feces and intestine.

Probiotics; Lactitol; Intestinal microbiota; Akkermansia; Mice