By Angela Biron
Although it might not look like it, ocean water is full of tiny marine microorganisms! While most of these microbes are harmless, some can infect humans. One species of infectious, or pathogenic, marine bacteria found in the Gulf of Maine is Vibrio parahaemolyticus. Animals like oysters that filter water to eat can pick up Vibrio when feeding. People can become infected if we eat raw or undercooked shellfish, like oysters, that contain Vibrio from the water. This infection causes symptoms like food poisoning, but usually does not become serious. Not only can this Vibrio make people sick, it can also prevent shellfish fisheries from being able to sell their products.
Because Vibrio are so tiny, we cannot count them with our eyes, or even a microscope. Instead, we use techniques in the lab that look at the genetic material, or DNA, that is present in the water samples. Not all Vibrio parahaemolyticus are pathogenic, so to determine whether they are, we look at the presence of a specific gene in their DNA. We can study this using a process called qPCR, which allows us to copy the gene many, many times if it is present in the water that we sample, so the amount present becomes detectable. qPCR is like a photocopier, that can stick to only the specific gene of the DNA, so will only make copies of that region in the genome.
We can then calculate how many cells of pathogenic Vibrio were in the original water sample that we took. After this, we can look at how these abundances relate to the temperature and salinity of the water at the time it was sampled, which are important environmental factors that are influenced by climate change — especially in the Gulf of Maine, which is warming faster than almost all other bodies of water on earth! Once we figure out how Vibrio relates to these environmental factors, we can make predictions and help reduce harm to human health and shellfish industries in Maine.
Angela Biron is a Colby College student in the 2020 Sea Change Semester Program at Bigelow Laboratory. This intensive experience provides an immersion in ocean research with an emphasis on hands-on, state-of-the-art methods and technologies.