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This content will become publicly available on August 26, 2018

Title: Effects of humic acid on the interactions between zinc oxide nanoparticles and bacterial biofilms

The effects of humic acid (HA) on interactions between ZnO nanoparticles (ZnO NPs) and Pseudomonas putida KT2440 biofilms at different maturity stages were investigated. Three stages of biofilm development were identified according to bacterial adenosine triphosphate (ATP) activity associated with biofilm development process. In the initial biofilm stage 1, the ATP content of bacteria was reduced by more than 90% when biofilms were exposed to ZnO NPs. But, in the mature biofilm stages 2 and 3, the ATP content was only slightly decreased. Biofilms at stage 3 exhibited less susceptibility to ZnO NPs than biofilms at stage 2. These results suggest that more mature biofilms have a significantly higher tolerance to ZnO NPs compared to young biofilms. In addition, biofilms with intact extracellular polymeric substances (EPS) showed higher tolerance to ZnO NPs than those without EPS, indicating that EPS play a key role in alleviating the toxic effects of ZnO NPs. In both pure ZnO NPs and ZnO-HA mixtures, dissolved Zn 2+ originating from the NPs significantly contributed to the overall toxicity. The presence of HA dramatically decreased the toxicity of ZnO NPs due to the binding of Zn 2+ on HA. Furthermore, the combined results from this work suggestmore » that the biofilm maturity stages and environmental constituents (such as humic acid) are important factors to consider when evaluating potential risks of NPs to ecological systems.« less
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Huazhong Agricultural Univ., Wuhan (China). College of Resources and Environment
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Earth and Biological Sciences Directorate
Publication Date:
Grant/Contract Number:
AC05-76RL01830; 41522106; 2016YFD0800206; 2015CB150504; 90001
Accepted Manuscript
Journal Name:
Environmental Pollution
Additional Journal Information:
Journal Volume: 231; Journal ID: ISSN 0269-7491
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; 60 APPLIED LIFE SCIENCES; Zinc oxide nanoparticle; Pseudomonas putida KT2440 biofilm; Different stages of maturity; Dissolved Zn2+; Humic acid
OSTI Identifier: