title: Limited microbial degradation of pyrene metabolites from the estuarine polychaete Nereis diversicolor.
abstract: We compared microbial mineralization of [4,5,9,10-14C]pyrene and its eukaryotic [4,5,9,10-14C]pyrene metabolites in estuarine sediments. Metabolites were obtained by exposing the estuarine deposit-feeding polychaete Nereis diversicolor to sediment-associated 14C-pyrene, followed by homogenization of the worms and extraction of the pyrene-metabolites. In sediment from a pristine Danish Fjord only 2.6% of the added metabolite-label and 1.7% of the pyrene-label were mineralized to 14CO2 during 175 days incubation. Pre-exposure of the pristine sediment to unlabelled pyrene for 60 days increased the mineralization potential for 14C-pyrene substantially, as 81.2% was mineralized to 14CO2 during 95 days incubation, whereas 14C-pyrene metabolite label was unaffected by pre-exposure to pyrene. In comparison, naturally aged bunker-oil contaminated sediment did not show elevated potentials for mineralization of neither 14C-pyrene nor 14C-metabolites. Six bacterial strains of known pyrene degraders were tested for growth on crystalline 1-hydroxypyrene. 1-Hydroxypyrene is the only intermediate eucaryotic metabolite of pyrene. The results indicate that 1-hydroxypyrene was not utilized as a sole source of carbon and energy by any of them. In addition, respiration was depressed in all six strains when exposed to crystalline 1-Hydroxypyrene, demonstrating an acute toxic effect of 1-hydroxypyrene. The results presented here suggest that microbial degradation of pyrene is not enhanced by release of aqueous and polar metabolites by marine invertebrates.
authors.affiliation: Department of Life Sciences and Chemistry, P.O. Box 260, Roskilde University, DK-4000 Roskilde, Denmark. anders@giessing.dk
authors.forename: Anders M B
authors.initials: AM
authors.lastname: Giessing
authors.forename: Anders R
authors.initials: AR
authors.lastname: Johnsen
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes / Q000032:analysis; D004785:Environmental Pollutants / Q000378:metabolism*; D019015:Geologic Sediments / Q000737:chemistry; D011077:Polychaeta / Q000378:metabolism*; D011721:Pyrenes / Q000378:metabolism*
chemical_list: D002250:Carbon Radioisotopes; D004785:Environmental Pollutants; D011721:Pyrenes; C033146:1-hydroxypyrene