I’ve run into some problems with getting my samples to grow continuously when I need them and to grow fast enough for my identifications. When I was trying to grow some of my samples from last semester up from frozen stocks, the media got contaminated and they all had to be discarded, much to my dismay. This one mistake alone set me back days as I had spent two days on that process and had to completely restart it the next day. Once things did grow, they occasionally would stop growing when I needed them. I work with a large variety of bacteria that are very different, so they all have different preferences and grow times. This makes my research very challenging and it does not always go as I planned.
I’ve had a lot of setbacks because of all of this and was not able to reach my goal of beginning the NAD/NADH glow assays before I the second blog post was due, but I will have them started before the fall semester resumes. I have about finished my bacterial identifications and I am researching ways to quantify PCB levels that are quick and affordable now. I had to leave town for a while to see family, so I had to wrap things up and I am just beginning to restart everything, which takes a long time.
We want to understand how the PCBS may be affecting the bacteria, but there is so little information about it, so I will be reviewing papers that describe the cellular changes that PCBs cause in humans then see if there are any analogous qualities in bacteria that could be causing changes. Hopefully this will help us understand the possible changes that may have occurred in the ecosystem in response to the PCB contamination.
My project is entitled Evaluation of Bacterial Redox Stress as a Marker for the Cellular Consequences of PCB Contamination in the Hudson River. To understand my project we must go back in time. The Hudson River was subject to Polychlorinated Biphenyl (PCB) pollution for about 30 years from the General Electric plant in Hudson Falls. Since the dumping, it has been discovered that PCBs are incredibly harmful to human and animal health. Only recently has there been any effort to remediate this damage when the EPA decided to dredge a large portion of the river, making it one of the largest Superfund sites. With all this research on the effects on animal health, bacteria in the river have been greatly neglected. Yamada et al (2006) has shown that exposure to biphenyls can lead to oxidative stress in bacteria that can lead to problems will cell separation, potentially leading to cell death. My research is testing the bacteria in the Hudson River to see if they are experiencing oxidative stress, potentially exhibiting a biomarker for PCB pollution in waterways. My research will also evaluate bacterial diversity along the superfund as compared to water from outside of the river. If the bacteria are still showing signs of oxidative stress after the river has been dredged, it could show a downfall of the type of remediation used on the Hudson and promote more effective methods of PCB removal. Healthy bacterial diversity is necessary for ecosystem services and can help keep potentially dangerous bacteria from being able to thrive in the river. Any imbalance to this, could ripple out into other parts of the ecosystem and make a lasting negative effect.
To test this, I have collected water samples from Hudson Falls to Troy, NY. I selected nine sites in total as well as two controls in Beacon, NY and Brooklyn, NY and sampled them in triplicate. Each sample is streaked out and allowed to grow for three days. After this time, two bacteria are selected from each sample. Using a BioLog system, I identified each of the colonies selected from the water samples. Our evaluation of bacterial/fungal diversity at the sites thus far has identified the following organisms: Bacillus krulwichiae (Snook Kill), Vogesella indigofera (Snook Kill), Massila dura (Snook Kill), Bacillus indicus (Snook Kill), Staphylococcus caprae (Snook Kill), Pediococcus acidilactici (Fort Edward), Corynebacterium capitovis (Fort Edward), Bacillus pseudomycodies/cereus (Fort Edward), Bacillus subtilis ss subtilis (Troy), Staphylococcus hyicus (Thompson Island Dam), Micrococcus luteus E (Beacon), Bacillus endophyticus (Beacon), Bacillus idriensis ( Beacon), Nocardia asteroids (Beacon), Bacillus cibi (Beacon), Brevibacillus borestlenis (Beacon), Macrococcus brunensis (Brooklyn), Aeromonas media (Brooklyn). Once all of the bacteria are identified, I will be using a Promega assay that evaluates the NAD/NADH ratios in the bacteria to quantify oxidative stress. We hypothesis that the bacteria will be accumulating NAD, meaning that it is in an oxidized state.