Volatile compounds-induced environmental pH shifts mediate interspecific bacterial interactions over long-distance

Microorganisms interact with each other through exchanging metabolites as well as signals molecules. This exchange typically depends on metabolites or signaling molecules diffusing in aqueous media within spatially connected habitats, and it only occurs within a short range. However, different microorganisms frequently live in spatially discontinuous micro-habitats without the connections of aqueous media. How microorganisms populating such spatially discontinuous micro-habitats interact remains poorly understood. Here, we show that a bacterial strain, Corynebacterium glutamicum ATCC13032T, produces high amounts of ammonia in its local habitat, which disperses over long distances (up to 12 cm) through the air. As a result, the pH of another spatially disconnected habitat increases, thus inducing the growth of an acid-sensitive strain (Glycocaulis alkaliphilus 6B-8T). We also show that ammonia-mediated long-distance interactions can be commonly found in various bacterial communities. In conclusion, our work demonstrates that bacteria growing in spatially discontinuous micro-habitats can interact with each other through gaseous diffusion of volatile compounds. This finding expands our understanding of the spatial scale at which bacteria can interact and provides new insights into how spatially separated species are connected to maximizing community-level commensalism.