Primary carbon sources and self-induced metabolic landscapes shape community structure in soil bacterial hotspots

Abstract

Direct observations of the complex and highly dynamic metabolic landscapes that affect the structure and functioning of bacterial communities in natural soil are limited by soil opacity and pore space complexity. In this study, we employ community metabolic network models to predict how the emerging bacterial community composition alters its structure and composition as a function of the primary carbon source in both well-mixed and spatially explicit systems. We provide systematic, experimental validation using a synthetic community comprised of four bacterial species grown on prescribed carbon sources and quantify their abundance using qPCR. Results suggest that community members may benefit from trophic interactions or suffer from increased competitive stress depending on the carbon source. The modeling is expanded to consider interactions in soil-like spatial context. Results show emergence of distinct bacterial community compositions as a function of primary carbon sources typical to soil hotspots (carbohydrates or organic acids). The ability to link genetic information with bacterial community trophic interactions in representative soil environments is a critical first step towards attaining predictability of soil ecological functioning.