Interactions of bacteria and diatoms in phototrophic biofilms

Lachlan Dow

Adrien Lapointe

Epilithic photoautotrophic biofilms are very important and productive ecological niches, which in the littoral zone of Lake Constance are dominated by benthic diatoms. We have isolated diatom strains together with associated satellite bacteria from these biofilms. Recent work shows that specific bacteria can influence carbohydrate production and thus biofilm formation of diatoms. Therefore this project is focused on the understanding of biotic interactions between diatoms and associated heterotrophic bacteria. A single satellite bacteria known to induce the formation of these biofilms is being studied, along with two freshwater diatom species: Achnanthidium minutissimum and Fragilaria brevistriata. Specifically, we are identifying both excretory signal molecules and bacterial genes necessary for such interkingdom signalling. In order to find potential genes, both genomic and transcriptomic methods are being employed, along with further studies of certain genes identified by Dr. Windler, which will hopefully lead to the identification of metabolites involved in biofilm formation.