This morning, the Marine Science Interns compared the bacterial content of different brands of bottled water. After arriving on station, the interns headed up to the micro-biology department to meet with scientists Rachel Parsons, Mae Lortie and Stephen Lightbourne. There, Ms. Parsons explained why scientists study micro-organisms such as bacteria and viruses and their importance to the marine environment. Mae and Stephen then led the interns into the lab and showed them how to test the presence and concentration of bacteria in a water sample using DAPI, a fluorescent dye which binds to DNA.
The interns tested 10 different brands of bottled water by taking a water sample, adding the DAPI solution to stain the cells and then passing the sample through a filter, which trapped bacteria. The interns then counted the number of bacteria present in 12 random locations under the microscope for each test sample. With the collected data, the interns calculated the total number of organisms present in the each sample.
The interns found that Smart Water, with 2,738 bacterium per liter, contained the fewest number of bacteria (left), while Evian, with 181,802 bacterium per liter, contained the most (right). But don't worry! All bottled water is treated with ultra violet light to kill the bacteria, so they're all perfectly safe. What it does show us is that different water sources, i.e. rain water vs. spring water, are unique environments, supporting their own micro-organism ecosystems.
Liam, who will be leaving for Wales tomorrow morning, commented that, "Today was the terminal day of the internship for me, and a great day for science! Our explorations into the bacterial contents of drinking water will change my beverage choices for the rest of my life. Also, I practiced coral identification on CPCe, slowly screening a video of a transect taken yesterday. It was more challenging on the video because of the limited resolution, so I had to adapt to identify corals by shape, size and colour as well as texture."