Changes in NADH,H+:NAD+ of Pseudomonas taetrolens may be used to assess the effectiveness of PCB dredging in the Hudson River

Abstract

The purpose of this study was to determine if a microbial biomarker for successful remediation of the polychlorinated biphenyl (PCB) contamination in the Hudson River could be identified by evaluating the cytoplasmic redox states of microorganisms isolated from the river. Studies have indicated that PCB exposure leads to oxidative stress in bacteria. Water samples were collected from the original dumping sites of PCBs and the following locations (Environmental Protection Agency (EPA) dredged locations are highlighted with year of dredging): Hudson Falls, Fort Edward Dam (2011), Thompson Island Dam (2014), Northumberland Dam (2012), Thomson (2013), Schuylerville Island, Saratoga National Park (2013), Lock 3 in Mechanicville (2015), and Federal Dam in Troy. Samples from Beacon, NY, and the East River at Brooklyn Bridge Park (130 miles downriver from the PCB contaminated sites) were collected as controls. Our evaluation of bacterial diversity at the sites led to the isolation of 33 bacteria, 28 of which were positively identified using a bacterial identification system. An analysis of the NAD+ and NADH,H+ concentrations and NADH,H+:NAD+ ratios across the isolated bacteria as a way to quantify cytoplasmic redox stress demonstrated that there was no significant difference in NAD+ and NADH,H+ concentrations or NADH,H+:NAD+ ratios between the organisms regardless of site dredging status. However, upon comparing NADH,H+:NAD+ ratios between matched bacterial isolates from undredged and dredged sites, we determined that the decrease in ratio by the PCB degrading bacterium, Pseudomonas taetrolens, approached significance (p = 0.065) suggesting that its presence at dredged sites may be used as an indicator of successful remediation.