A 15-day biodiversity intervention with horses in a farm system leads to acquisition of health-promoting features in the gut microbiome of 10 urban Italian children

Abstract In order to evaluate the possibility to shape the human gut microbiome (GM) through the interaction with natural ecosystems, we explored the impact of a 15-day biodiversity intervention with horses on the GM of 10 urban-living Italian children. The children GM was metagenomically assessed before and after 10hr/day daily interaction with horses in an educational farm. The horses’ skin, oral, and fecal microbiomes were similarly assessed as well. We found that the interaction with horses facilitates the acquisition of health promoting features in the children GM, such as a higher diversity, an enhanced production of butyrate and the increase of several health-promoting species, generally considered as next-generation probiotics. Amongst these, the butyrate producers Facecalibacterium prausnitzii and F. ducaniae and a species belonging to the anti-inflammatory Christensenellales. Moreover, the interaction with horses were also associating with the increase of GM components exerting important roles in the bioconversion of dietary plant polyphenols to health promoting and protective metabolites, as Eggerthella lenta, Gordonibacter pamelae and G. urolithifacens. Supporting the microbiological safety of the interaction process, we did not observe any increases pathogenic features in the children GM following the interaction with horses. Overall, our pilot study provides insights into the existence of possible health-promoting variations in the GM from urban-living children thanks to the interactions with horses. This lays the foundations to explore the full extent of the beneficial interaction process occurring between the human GM and the natural microbiomes.