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

Abstract

Many marine infaunal hemichordates and polychaetes produce volatile halogenated secondary metabolites, including several brominated aromatic compounds. These compounds have been suggested to have antimicrobial activity. However, the impact of added bromometabol~tes on microbial activities in undisturbed sediments has not been assessed. This study examines the effects of a common bromometabolite, 4-bromophenol, on substrate respiration and assimilation by undisturbed sediment bacterial communities. Intact sediment cores were collected from a site inhabited by the bromophenol producing capitellid polychaete Notomastus lobatus and from a similar site having no bromometabolite producing infauna. These cores were injected with a radiolabeled suhstrate (acetate or glucose) and varying levels of 4-bromophenol, then incubated at ~n situ temperature. Rates of respiration and assimilation of the substrates at levels of 4-bromophenol ranging from ambient to 10 pg g-' (dry weight) sediment were determined. No significant inhibition of respiration or assimilation of either substrate was observed in samples from either location, even at 4-bromophenol levels lOOx the ambient concentration in wormbed sediments. These data show that this naturally occurring bromoaromatic compound has no significant effect on community activity of sediment bacteria.