Abstract: Background: Intestinal microbiota can affect human health through various ways and is related to the occurrence of diseases. There are obvious differences in the composition of intestinal microbiota in different regions. Objective: To compare the difference of intestinal microbial composition among healthy preschool child in northern and southern China by 16S rRNA gene sequencing method. Methods: Children aged 3-7 years who underwent physical examination at the physical examination center of Foshan Chancheng Hospital in Foshan City, Guangdong Province were selected as the southern group, and children from a kindergarten in Tacheng District of Xinjiang Uygur Autonomous Region were selected as the northern group. Stool samples of all preschool children were collected by their parents after training, and intestinal flora detection and related data analysis were completed by Hangzhou Guhe Information Technology Co., LTD. Main outcome measures: Microbial diversity, as well as differences in species composition. Results: From February 1, 2023 to April 1, 2023, 45 children aged (4.0±1.5) years were included in the southern group. In the northern group, 45 cases were included, of which 2 were unqualified, and the remaining 43 were (4.1±1.3) years old. There were no significant differences in gender, age and ethnic composition between the two groups. The Alpha diversity indexes including Shannon, Simpson, Chao and ACE of the northern group were higher than those of the southern group with statistically significant differences between two groups. The weighted unifrac PCoA plot showed a significant separation between the two group samples. The abundance of Firmicutes in the northern group was higher than that in the southern group (55.1% vs 39.2%), and the abundance of Proteobacteria in the southern group was higher than that in the northern group (18.6% vs 7.2%). The abundance of Eubacterium-eligens-group in southern group was higher than that in northern group (11.8% vs 2.2%), and the abundance of Faecalibacterium in the northern group was higher than that in the southern group (13.9% vs 6.3%). The differences were statistically significant. LEfSe analysis and random forest intergroup prediction revealed that statistically different biomarkers were Escherichia-Shigella and Ruminococcus-gnavus group for the southern group and Faecalibacterium, Agathobacter, Lachnospira, Senegalimassilia, Subdoligranulum, Eubacterium-eligens-group,Parasutterella, Dialiste and Rseburia for the northern group. Conclusion: There are significant differences in the intestinal flora of preschool children in the north and south of China. The regionality of the host should be fully considered in the future research on intestinal flora and diseases.

Key words: Intestinal microbes, Region, Preschool child