Kavli Affiliate: Robert Edwards
| Authors: Joel E Brame, Craig Liddicoat, Catherine A Abbott, Robert A Edwards, Jake M Robinson, Nicolas E Gauthier and Martin F Breed
| Summary:
Abstract Butyrate-producing bacteria are found in many ecosystems and organisms, including humans. They ferment organic matter, producing the by-product butyrate, a short-chain fatty acid with important roles in human health. Several human diseases have been associated with a decreased abundance of butyrate-producing bacteria in the gut. Outdoor environments can potentially replenish the abundance of these commensal bacteria in humans. However, the environmental sources and exposure pathways remain poorly understood. Here we developed new normalized Butyrate Production Capacity (BPC) indices derived from global metagenomic (n=16,176) and Australian soil 16S rRNA (n=1,285) data to geographically detail the environments that associate with bacterial butyrate production potential. We show that the highest BPC scores were in anoxic and fermentative environments, including plant rhizospheres and the gut of vertebrates. Among land types, higher BPC scores were in soils from temperate urban hinterlands and bogs. Climatic and geographical variables were the primary drivers of BPC score variation across land types. We show that the potential for ambient human exposure to health-promoting butyrate-producing bacteria should be highest in residential woodlands, dense urban environments with moderate rainfall, and particular pastures and croplands. This new biogeographic understanding of how and where humans are exposed to these important health-promoting microbes should be integrated into health and environmental policies to improve public health outcomes. Competing Interest Statement The authors have declared no competing interest.