Dr. Steven Greimman is an assistant professor at Georgia Southern in the biology department. He is a classically trained parasitologist currently specializing in taxonomy and systematics which means he describes new species of parasites. This includes endoparasites, tapeworms, flukes, flatworms that live inside of animals and humans. He describes it based on how they look, their morphology, but also sequences their DNA and looks at their evolutionary relatedness between each other. Recently Greiman's research has taken him to the lab a lot, looking at microbiomes, which is the community of the bacteria and all the parasites in animals and How that kind of changes over time.
Greiman has several projects that he is currently working on. One with a Georgia Sea Grant which is part of NOAH looking at oyster parasites and pathogens and population genetics, so they are screening a lot of oysters off the coast of Georgia for these different parasites that live on the gills and can cause the death of the oysters as well as bacteria that can be transmitted from the oysters to humans. Another funded project is with the Georgia DNR (The Department of Natural Resources) looking at natural resources looking at white shrimp. They do E-DNA studies trying to pick up DNA in the water to show that the white shrimp are there and how much of the white shrimp are present. These are the two projects currently being funded.
In Greiman's lab, he has graduate students that are describing new species of tapeworms from shrews from Mongolia and New Mexico and then all over the US and looking at their evolution so how they're related to one another and to other tapeworms.
Greiman said that the oyster project is his favorite and walked me through the process of what his team does. He works in collaboration with Dr. John K Carol who is also in the Biology department at Georgia Southern. Carol goes out to collect all the oysters from different reefs off the coast of Georgia. Some from Skidaway islands and Sathlow islands which involves taking a boat, “This summer they will begin collecting every week to conduct a summer study”.The collected oysters are brought back to Carol's lab. They then shuck them and remove the tissue and freezes the tissue as well as fixing them in ethanol.
Greiman's job, along with his graduate students is to extract the DNA from the oyster tissue and then they use real-time PCR which is the real thing you use for covid testing when swabbing the throat. The goal is to look for the oyster pathogen within the extraction, “We have special primers to amplify the DNA and if it’s present you'll see it show up in the reaction”. They do it for two protozoan parasites which are single-celled organisms that live in the gills, but they cause damage to the oysters.
Because you can use the screening to search for many things, Greiman also uses it to search for bacteria. “If someone were to eat an oyster with bacteria present, it could actually kill them”.
Usually, this occurs in warm water oysters which is why you cannot buy fresh oysters during the summer in Georgia. Greiman looks at what time of the year is worse for these species of bacteria and if it increases over summer or not.