Activity of marine sediment bacterial communities exposed to 4-bromophenol, a polychaete secondary metabolite

Many marine infaunal hemichordates and polychaetes produce volatile halogen ated secondary metabolites, including several brominated aromatic compounds . These compounds have been suggested to have antimicrobial activity. Howev er, the impact of added bromometabolites on microbial activities in undistu rbed sediments has not been assessed. This study examines the effects of a common bromometabolite, 4-bromophenol, on substrate respiration and assimil ation by undisturbed sediment bacterial communities. Intact sediment cores were collected from a site inhabited by the bromophenol producing capitelli d polychaete Notomastus lobatus and from a similar site having no bromometa bolite producing infauna. These cores were injected with a radiolabeled sub strate (acetate or glucose) and varying levels of 4-bromophenol, then incub ated at in situ temperature. Rates of respiration and assimilation of the s ubstrates at levels of 4-bromophenol ranging from ambient to 10 mu g g(-1) (dry weight) sediment were determined. No significant inhibition of respira tion or assimilation of either substrate was observed in samples from eithe r location, even at 4-bromophenol levels 100 x the ambient concentration in wormbed sediments. These data show that this naturally occurring bromoarom atic compound has no significant effect on community activity of sediment b acteria.