Variation of faecal microbiota in dogs during ageing

The composition of the gut microbial population fluctuates during life and changes are expected with ageing. However,several confounding factors have to be considered,since breed, diet, onset of degenerative disease and environmental situations can affect the gut microbiota and are not easy to control on longitudinal study.In this research,fecal samples from 150 Beagle dogs housed in the same kennel and fed the same diet were collected in a 30 days span time and analysed for microbiota composition. Dogs were grouped as young (30 dogs, from 20 to 46 months), adult (44 dogs, from 47 to 92 months and old (76 dogs, 93 to 168 months). After DNA extraction, the V3-V4 hypervariable regions of the 16s rRNA gene were sequenced in a 250 PE mode with Illumina Novaseq platform. FASTQ files were uploaded in QIIME2 for taxonomic annotations, based on the greengene classifier, trained on the amplified regions.The alpha and beta diversities did not vary between young, adult and old groups of dogs. The analysis of LDA Effect Size (LEfSe)on the relative abundances of taxa showed significant differences for the Burkholderiales, Eryisipleotrichaceae, and Clostridiales in young dogs.The taxa of S24_7,Peptococcus, Ruminocaoccaceae, Bacteroidales, Peptostreptococcus, Eubacterium and Lachnospira significantly differ in adult dogs, whilst Sutterella and Clostridium prevailed in old dogs. The observed shifts of the relative abundance of these taxa with ageing suggest that the gut microbiota can be regulated by ageing, although the meaning of these changes deserves further investigation.