title: Response of soil microorganisms to As-produced and functionalized single-wall carbon nanotubes (SWNTs).
abstract: The use of single-wall carbon nanotubes (SWNTs) in manufacturing and biomedical applications is increasing at a rapid rate; however data on the effects of a potential environmental release of the materials remain sparse. In this study, soils with either low or high organic matter contents as well as pure cultures of E. coli are challenged with either raw as-produced SWNTs (AP-SWNTs) or SWNTs functionalized with either polyethyleneglycol (PEG-SWNTs) or m-polyaminobenzene sulfonic acid (PABS-SWNTs). To mimic chronic exposure, the soil systems were challenged weekly for six weeks; microbial activities and community structures for both the prokaryote and eukaryote community were evaluated. Results show that repeated applications of AP-SWNTs can affect microbial community structures and induce minor changes in soil metabolic activity in the low organic matter systems. Toxicity of the three types of SWNTs was also assessed in liquid cultures using a bioluminescent E. coli-O157:H7 strain. Although decreases in light were detected in all treated samples, low light recovery following glucose addition in AP-SWNTs treatment and light absorption property of SWNTs particles suggest that AP-SWNTs suppressed metabolic activity of the E. coli, whereas the two functionalized SWNTs are less toxic. The metals released from the raw forms of SWNTs would not play a role in the effects seen in soil or the pure culture. We suggest that sorption to soil organic matter plays a controlling role in the soil microbiological responses to these nanomaterials.
authors.affiliation: Laboratory for Soil Microbiology, College of Agriculture, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Tong
authors.forename: Marianne
authors.initials: M
authors.lastname: Bischoff
authors.forename: Loring F
authors.initials: LF
authors.lastname: Nies
authors.forename: Phillip
authors.initials: P
authors.lastname: Myer
authors.forename: Bruce
authors.initials: B
authors.lastname: Applegate
authors.forename: Ronald F
authors.initials: RF
authors.lastname: Turco
mesh_terms: D018533:Biomass; D002245:Carbon Dioxide / Q000378:metabolism; D058645:Denaturing Gradient Gel Electrophoresis; D004926:Escherichia coli / Q000378:metabolism; D008163:Luminescent Measurements; D008670:Metals / Q000737:chemistry; D008969:Molecular Sequence Data; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D012987:Soil; D012988:Soil Microbiology; D013451:Sulfonic Acids / Q000737:chemistry
chemical_list: D008670:Metals; D037742:Nanotubes, Carbon; D012987:Soil; D013451:Sulfonic Acids; D002245:Carbon Dioxide; D011092:Polyethylene Glycols