Diatom exudates influence metabolism and cell growth of co-cultured diatom species

We surveyed the role of chemically mediated interactions between the 2 diatom species Skeletonema costatum and Thalassiosira weissflogii. S. costatum promoted the growth of T weissflogii in non-contact co-cultures, allowing an exchange of exuded metabolites. In contrast, cell counts of S. costatum were not affected by T weissflogii. Metabolic profiling of the co-culture medium revealed a significant change in diatom-derived metabolites in comparison with those of monoculture controls. Several compounds detected in monocultures were not present in the co-culturing set-up, indicating either a transformation or uptake of released metabolites by the competing species. In addition, metabolic profiling of intracellular metabolites revealed that the biochemical processes of both diatoms changed in the presence of the co-cultured species. The present study illustrates that chemical cross-talk between diatom species is possible and that these types of chemical interactions lead to physiological responses and might even result in changed cell abundances.