Microbial community structuring by 2-heptyl-4-quinolone (HHQ) during a phytoplankton bloom at the Espeland Marine Biological Station in Bergen, Norway

Algicidal infochemicals produced by marine bacteria have the unique ability to influence the structure of prokaryotic and eukaryotic microbial communities simultaneously. 2-heptyl-4-quinolone (HHQ), a quorum-sensing molecule produced by the marine Gammaproteobacterium Pseudoalteromonas piscicida, was recently shown to arrest the growth of certain eukaryotic phytoplankton. To investigate effects of HHQ in-situ, we exposed natural microbial communities from the Norwegian coast to nanomolar concentrations of HHQ over the course of a phytoplankton bloom. Amplicon sequencing (16S and 18S rRNA genes) revealed distinct patterns in both free-living and particle-associated bacteria and eukaryotic phytoplankton community structure.