BackgroundGut microbiota is closely related to age. Studies from Europe and the U.S. identified featured microbiota in different age groups for the elderly. Asian studies mainly focused on people living in longevity areas. Featured microbiota for the elderly people of different age groups, especially in the centenarian in the general population, has not been well investigated in China.MethodWe conducted a comparative study by including 198 subjects of three age groups (65–70, 90–99, and 100+ years) in East China. Information regarding age, sex, height, weight, waist circumference, hip circumference, food preference, smoking status and alcohol consumption were collected by using a structured questionnaire. Fecal samples for each participant were collected as well. 16S rRNA gene sequencing were employed to analyze the gut microbiota composition. Logistic regression with LASSO feature selection was used to identify featured taxa in different age groups and to assess their potential interactions with other factors such as lifestyle.ResultThe gut microbiota of the 90–99 year and 100+ year age groups showed more diversity, robustness, and richness compared with the 65–70 year age group. PCoA analysis showed a clear separation between the 65–70 and 100+ year age groups. At the species level, Bacteroides fragilis, Parabacteroides merdae, Ruminococcus gnavus, Coprococcus and Clostridium perfringens increased, but Bacteroides vulgatus, Ruminococcus sp.5139BFAA and Clostridium sp.AT5 decreased in the 90–99 year age group. The age differences in gut microbiota were similar across the strata of smoking, alcohol consumption status and food preference.ConclusionOur study demonstrated age differences in many aspects of gut microbiota, such as overall diversity, microbiota structure, and relative abundance of key taxa. Moreover, the gut microbiota of centenarian was significantly different from those of younger age groups of the elderly.