Background:Imbalance of intestinal microbiota was closely related to colitis.Under these circumstances,regulation of enteric flora may be beneficial to the repair of inflammation.We aimed to investigate the effects of probiotics (Bifidobacterium and Lactobacillus),prebiotics and their combination on inflammation,and microflora in mice of acute colitis.Methods:C57BL/6J mice were divided into six groups randomly (blank control group,model control group,probiotics group,synbiotics group,lactitol group and probiotics + lactitol group).Each group was given 2.5％ dextran sulfate sodium drinking water for 5 days other than the blank control group.Except for the model control group,the other four groups were intervened with probiotics,synbiotics (probiotics and inulin),lactitol,and probiotics + lactitol.Mice were sacrificed after 1 week of gavage,and pathologic scores were calculated.The feces of different periods and intestinal mucosa samples were collected to analyze the differences of intestinal microbiota by 16S rRNA sequencing.Differences of two groups or multiple groups were statistically examined through unpaired Student t test and analysis of variance (ANOVA),respectively.ANOVA,Tukey,Anosim,and metastats analysis were used to compare differences of microbiota among different groups.Results:After gavage for 1 week,the pathologic scores of groups with the intervention were significantly lower than those in the model control group,and the difference was statistically significant (P ＜ 0.05).The model control group was higher in the genus of Bacteroides (relative abundance:0.3679 vs.0.0099,P =0.0016) and lower in Lactobacillus (relative abundance:0.0020 vs.0.0122,P =0.0188),Roseburia (relative abundance:0.0004 vs.0.0109,P =0.0157),compared with the blank control group.However,the same phenomenon was not found in groups gavaged with probiotics and lactitol.Compared with model control group,mice with intervention were increased with Bifidobacterium (relative abundance:0.0172 vs.0.0039,P =0.0139),Lachnospiraceae_NK4A136_group (relative abundance:0.1139 vs.0.0320,P =0.0344),Lachnospiraceae_UCG-006 (relative abundance:0.0432 vs.0.0054,P =0.0454),and decreased with Alistipes (relative abundance:0.0036 vs.0.0105,P =0.0207) in varying degrees.The mucosal flora was more abundant than the fecal flora,and genus of Mucispirillum (relative abundance:0.0207 vs.0.0001,P =0.0034) was more common in the mucosa.Lactitol group showed higher level of Akkermansia than model control group (relative abundance:0.0138 vs.0.0055,P =0.0415),probiotics group (relative abundance:0.0138 vs.0.0022,P =0.0041),and synbiotics group (relative abundance:0.0138 vs.0.0011,P =0.0034),while probiotics + lactitol group had more abundant Akkermansia than synbiotics group (relative abundance:0.0215 vs.0.0013,P =0.0315).Conclusions:Probiotics and prebiotics reduce the degree of inflammation in acute colitis mice obviously.Mice with acute colitis show reduced beneficial genera and increased harmful genera.Supplementation of probiotics and prebiotics display the advantage of increasing the proportion of helpful bacteria and regulating the balance of intestinal microbiota.Lactitol might promote the proliferation of Akkermansia.