Respiration and Assimilation of 4-Bromophenol by Estuarine Sediment Bacteria

Abstract

A variety of infaunal marine polychaete and hemichordate species produce brominated secondary metabolites, particularly bromophenols, bromopyrroles, and bromobenzylalcohols. Rates of¹⁴C-4-bromophenol respiration and assimilation by sediment microflora were determined in intact cores taken from a site inhabited by the bromophenol-producing polychaete, Notomastus lobatus, and from a similar site having very low levels of bromophenols. Rates were similar at both locations, ranging from 6 to 87 pmole ml⁻¹ h⁻¹ for respiration, and from 13 to 35 pmole ml⁻¹ h⁻¹ for assimilation. Respiration rates exhibited strong seasonal variation, consistent with results of temperature response experiments, while assimilation rates showed less seasonal variation. Calculated areal rates of bromophenol degradation (to a sediment depth of 6 cm) ranged from 2.0 to 7.8 μmole m⁻² h⁻¹, equivalent to 350–1,250 μg m⁻² h⁻¹, indicating an important role for sediment bacteria in turnover of these compounds. Similar rates of bromophenol degradation at bromophenol-containing and non-bromophenol-containing locations show that adaptation of sediment bacteria by prior exposure to bromophenols is not required for degradation of these compounds.