title: Environmental biodegradability of [¹⁴C] single-walled carbon nanotubes by Trametes versicolor and natural microbial cultures found in New Bedford Harbor sediment and aerated wastewater treatment plant sludge.
abstract: Little is known about environmental biodegradability or biotransformations of single-walled carbon nanotubes (SWNT). Because of their strong association with aquatic organic matter, detailed knowledge of the ultimate fate and persistence of SWNT requires investigation of possible biotransformations (i.e., biodegradation) in environmental media. In the present study, [(14)C]SWNT were utilized to track biodegradation over 6 mo by pure liquid culture of the fungus Trametes versicolor and mixed bacterial isolates from field-collected sediment or aerated wastewater treatment plant sludge. The mixed cultures were chosen as more environmentally relevant media where SWNT will likely be deposited under both aerobic and anaerobic conditions. Activity of [(14)C] was assessed in solid, aqueous, and (14)CO2 gaseous phases to determine amounts of intact SWNT, partially soluble SWNT degradation products, and mineralized SWNT, respectively, during the 6 mo of the experiment. Mass balances based on radiocarbon activity were approximately 100% over 6 mo, and no significant degradation of SWNT was observed. Approximately 99% of the [(14)C] activity remained in the solid phase, 0.8% in the aqueous phase, and less than 0.1% was mineralized to (14)CO2, regardless of culture type. These results suggest that SWNT are not readily biodegraded by pure fungal cultures or environmental microbial communities, and are likely persistent in environmental media.
authors.affiliation: Nicholas School of the Environment, Duke University, Durham, North Carolina, USA; Center for the Environmental Implications of NanoTechnology, Duke University, Durham, North Carolina, USA; Office of Research and Development, National Health and Environmental Effects Research Laboratory-Atlantic Ecology Division, US Environmental Protection Agency, Narragansett, Rhode Island, USA.
authors.forename: Ashley N
authors.initials: AN
authors.lastname: Parks
authors.forename: G Thomas
authors.initials: GT
authors.lastname: Chandler
authors.forename: Kay T
authors.initials: KT
authors.lastname: Ho
authors.forename: Robert M
authors.initials: RM
authors.lastname: Burgess
authors.forename: P Lee
authors.initials: PL
authors.lastname: Ferguson
mesh_terms: D000332:Aerobiosis; D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002250:Carbon Radioisotopes; D019015:Geologic Sediments / Q000382:microbiology*; D008404:Massachusetts; D037742:Nanotubes, Carbon / Q000737:chemistry*; D012722:Sewage / Q000382:microbiology*; D055454:Trametes / Q000378:metabolism*; D062065:Wastewater / Q000382:microbiology*; D018508:Water Purification / Q000379:methods*
chemical_list: D002250:Carbon Radioisotopes; D037742:Nanotubes, Carbon; D012722:Sewage; D062065:Wastewater
keywords: Aerated sewage sludge; Biodegradation; Fungi; New Bedford Harbor sediments; Single-walled carbon nanotubes