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NCER Grantee Research Project Results

Advancing Techniques to Link Microbial Community Structure with Function to Assess the Impact of Emerging Contaminants using f-CNTs as Model Compounds

EPA Grant Number: FP917146
Title: Advancing Techniques to Link Microbial Community Structure with Function to Assess the Impact of Emerging Contaminants using f-CNTs as Model Compounds
Investigators: Nyberg, Leila Margaret
Institution: Purdue University - Main Campus
EPA Project Officer: Cobbs-Green, Gladys M.
Project Period: August 16, 2010 through August 15, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010)
Research Category: Academic Fellowships , Fellowship - Pesticides and Toxic Substances

Description:

Objective:

My objective is to determine the effect of functionalized single-walled carbon nanotubes such as SWNT-PEG and SWNT-COOH on the structure and function of an anaerobic microbial community, in addition to directly assessing the bioavailability of SWNT-PEG. My first hypothesis is that community function will be affected by exposure to the functionalized nanotubes (f-CNTs), and my second hypothesis is that microbial community structure will be affected as well. Finally, I hypothesize that PEG diol dehydratase will be induced in response to SWNT-PEG.

Synopsis:

The environmental impact of single-walled carbon nanotubes (SWNT) is largely unknown. In this study, microorganisms from an anaerobic wastewater treatment digester are exposed to SWNT functionalized with carboxyl groups (-COOH) and polyethylene glycol (-PEG). Gas formation is monitored and genetic tests are used to generate a microbial community fingerprint, in order to determine whether or not these new materials affect the structure and function of the microbial community.

Approach:

Anaerobic digester sludge from the Greater Lafayette wastewater treatment plant is used to construct microcosms, which are exposed to SWNT-PEG and SWNT-COOH. All treatments and reference samples are assembled in triplicate. Community function is assessed by monitoring gas formation (methanogenesis), detecting genes related to methanogenesis and acetogenesis, and using the diol dehydratase assay. Community structure is assessed by using polymerase chain reaction with denaturing gradient gel electrophoresis (PCR-DGGE). Domain-level as well as group-specific primers will be used to detect microbial community shifts.

Expected Results:

Preliminary results show that SWNT-COOH significantly increases gas formation, with DGGE results showing microbial community shifts over time. Continuing this analysis will elucidate the effect of SWNT-COOH over exposure times of a few months, while determining whether or not SWNT-PEG becomes bioavailable and exerts an impact on the microbial community over a longer period of time. This information will contribute to risk assessment of nanomaterials and inform their responsible manufacture and disposal.

Potential to Further Environmental/Human Health Protection:

Anaerobic digester microbial communities are receptors for emerging contaminants such as nanomaterials. These engineered microbial communities serve as important model systems for other anaerobic communities found in soil, in sediment, and in the stomachs of ruminant animals. Land application of sludge biosolids, and the importance of maintaining effective wastewater treatment systems, make understanding the effects of new chemicals in such environments important for human health as well as environmental management.

Supplemental Keywords:

nanomaterials, nanotoxicology, anaerobic, emerging contaminants, nanotubes, wastewater treatment, molecular genetics,

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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