The gut microbiome of old people in a Portuguese population is associated with Rural-Urban residence: impact on the metabolic profile and functionality

Background The gut microbiome mirrors unique characteristics of different locations and lifestyle, and old adults experience alterations in the gut microbiome potentially associated with the living setting. This study aimed to characterize the intestinal microbiome and examine the metabolite profile of older adults residents in rural and urban areas of Algarve, Southern of Portugal. Methods The 16 S rRNA sequencing was done using the Oxford Nanopore system and diversity indices were determined follow with the determination of the fecal total bile acid (TBA) and short chain fatty acids (SCFA). Results The findings indicate no significant differences between the α-diversity between the Old people, Middle Age and Young groups; however, the rural old group showed the highest diversity in comparison with the urban old group. The old individuals living in rural areas showed the highest absolute frequency of beneficial bacterial members, such as Blautia luti and Faecalibacterium duncaniae . Specific bacterial markers were identified for each age group analyzed with the highest number displayed by the rural old individuals. TBA content in the rural and urban old individuals was similar ( p > 0.05). Acetate levels were higher in urban old individuals ( p = 0.039). Fecal lactate levels were higher ( p < 0.001) in the old group, and the less functional old individuals showed higher lactate levels in comparison with the Middle Age and Young groups. Conclusion This study highlights distinct bacterial patterns in the gut microbiome of rural and urban old people with impact on microbial metabolic profile with potential consequences to their functionality. These findings may guide microbiota-diet-based strategies to promote healthy aging.