Electrochemical Removal of Bacterial DNA and Antibiotic Resistance Genes with Multi-Walled Carbon Nanotube Filters
Abstract
Antibiotic resistant genes in wastewater may be introduced into water cycle and pose serious health risks to humans. Many studies have been done to inactivate bacteria in wastewater but there are only limited studies on removal of antibiotic resistant genes. The objective of this study is to evaluate electrochemical removal of bacterial DNAs and antibiotic resistance genes from wastewater. An electrochemical multi-walled carbon nanotube filter was developed and the effects of applied potentials, pH, phosphate, and natural organic matter were evaluated. Total DNA concentration was quantified with Nanodrop and abundance of genes were quantified with real-time PCR. Agarose gel electrophoresis was used to evaluate DNA damage after electrochemical filtration. An applied potential of 0.75 V (vs Ag/AgCl) significantly improved the removal of DNA from 20% to above 60% and neutral pH was identified as the optimal pH for DNA removal. The addition of phosphate ions significantly improved DNA removal efficiency from 60% to over 80%. Addition of 5 ppm and 10 ppm natural matter increased DNA removal efficiency by about 7% after 30 mins of electrochemical filtration, but removal efficiency with 20 ppm natural organic matter decreased by 11%, suggesting that natural organic matter plays an important role in electrochemical removal of bacterial DNA. Real-time quantitative PCR analysis showed that 25 mins of electrochemical filtration achieved 4.0-log and 3.5-log removal for 16S rRNA gene and erm80 resistance gene, respectively, suggesting that electrochemical filtration was effective to remove antibiotic resistance genes. Overall the results suggest that electrochemical carbon nanotube filtration is a promising technique to remove bacterial DNA and antibiotic resistance genes. The mechanism of the interaction between DNA molecules and multi-walled carbon nanotube filters during electrochemical filtration needs further investigation.
Degree
M.S.
Advisors
Blatchley, Purdue University.
Subject Area
Civil engineering
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