Synthetic multispecies microbial communities reveals shifts in secondary metabolism and facilitates cryptic natural product discovery.

Chemically mediated interactions have been hypothesized to be essential for ecosystem functioning as co-occurring organisms can influence the performance of each other by metabolic means. Here, we present a co-culture device that allows co-culturing of microorganisms that are physically separated but can exchange chemical signals and metabolites. This setup was adopted to perform investigations on the secondary metabolisms of both a fungal-bacterial community and an actinomycetic-actinomycetic community. This study employed a metabolomics approach integrating LC-MS profiling, multivariate data analysis and molecular networking techniques. LC-MS measurements revealed a pronounced influence of such chemical communication on the metabolic profiles of synthetic co-culture communities with a group of molecules being induced or upregulated in co-cultures. A novel antibiotic exhibiting antibiotic properties against Klebsiella pneumoniae was unveiled in the fungal-bacterial community. Besides, a further survey of the fungal-bacterial cross-talk indicated that the production of co-culture-induced diphenyl ethers by fungi might result from the fungal response against the secretion of surfactins by bacteria in the cross-talk. This study demonstrated that the presented co-culture device and the metabolomic routine would facilitate the investigation on chemically mediated interactions in nature as well as cryptic natural products discovery.