About This ProjectOur main research goal is to isolate and identify the chemical or biological agents that protect the earthworm egg capsules from harmful fungal infections. Earthworms are diverse soil organisms found in fertile soils worlwide, except Antarctica. We study the interactions and benefits of microorganisms that live inside earthworms. In my lab, we work with a common composting worm Eisenia fetida, a.k.a. the red wiggler. These little guys are amazing with the capacity to degrade paper, wood shavings, grass, leaves and food scraps. They also resist infections. The compost pile is teeming with potentially harmful microbes, including fungi and protozoans that could infect and kill either the adult earthworms or their eggs. The earthworms deposit their egg capsules directly into the soils or compost, and there they develop to hatching with no additional protection. If we cure them of their beneficial bacteria the capsules become overgrown with fungi and do not hatch. This indicates there are bacteria in or on the capsules producing antifungal compounds protecting the eggs. With this funding we will concentrate, isolate and identify the chemicals with antifungal activity.
Ask the ScientistsJoin The Discussion
What is the context of this research?
What are the compounds produced in earthworm egg capsules that protect them from bacteria and fungi in composts and soils? Who is making these chemicals?
We will grow, isolate and identify bacteria and fungi that inhibit the growth of fungi found in soils and composts. We will also take crude extracts from earthworm egg capsules and test these extracts for fungal inhibition. After confirming activity, the active compounds will be analyzed for composition and structure.
What is the significance of this project?
We are facing a crisis: The need for new antibiotics, but a lack of companies interested in investing in research to discover them. New sources of antibiotics are needed, especially with the appearance of antibiotic resistant superbugs. However, antibiotics are perceived to be common and cheap, so companies risk a lack of high profits from researching new ones. These problems were highlighted in a recent article posted on Reuters.
Treatments for fungal infections are especially problematic, and new drugs to treat these are very important. Systemic yeast infections are a risk for immune-compromised patients, and fungal lung infections can be extremely difficult to treat. This is why funding research based on observations made in my lab is important. The research could lead to potent additions to our antimicrobial arsenal at a time when many large companies have moved on to more lucrative areas of drug development.
I have been working with the beneficial bacteria living in earthworms for a little over a decade. An important observation we’ve made is that their egg capsules that contain the developing worms rarely become overgrown with either fungi or pathogenic bacteria. The symbiotic bacteria are placed inside and on the surfaces of the egg capsules by the parent worms. These bacteria are producing antibiotics that protect the fragile embryos from the fungi, bacteria and protozoans that threaten to invade and consume an earthworm egg.
This tells us that the egg capsules are well-protected against fungi and bacteria. If we treat them with antibiotics to kill the bacteria in the egg capsule, then they are quickly overgrown by fungi. The next step is to identify the compounds and their producers.
What are the goals of the project?
With this funding, we will isolate bacteria and fungi that show antifungal activity. After we have identified isolates with inhibitory activity, we will grow up cultures and extract chemicals from these. In addition, we will extract the chemicals from the egg capsules directly. Then, this crude extract will be separated using thin layer chromatography and the chromatogram strip used to challenge bacteria by spreading cells onto agar medium and laying the strip onto the agar. As the bacteria grow up overnight, patches of inhibition will be revealed.
Another way we will test for inhibition is to extract chemicals from the egg capsules, concentrate these, then soak a small filter disc with the extracts and place onto bacterial spread plate, again looking for zones of no growth.
Extracts from the egg capsules and active bacterial cultures will be analyzed for chemical composition in a well-established natural products chemistry lab through collaboration with Eric Schmidt at the University of Utah. Eric and I have previously worked together, years ago, on a project to identify the bacteria producing bioactive compounds in a marine sponge.
The funds will be used to purchase general lab supplies (worm culture supplies, bacterial culture supplies, solvents for extracts), provide salary for researchers, and some fees for preliminary chemical analysis of the crude extracts (separation and activity testing).
Meet the Team
B.A. Biology University of Oregon, R. D. Clark Honors College
Seana is a Research Assistant Professor in the Environmental Engineering program at the University of Washington. She's been studying symbioses between invertebrates and bacteria for the past 17 years. In graduate school she discovered the bacteria that produce anticancer compounds in an inconspicuous marine animal. At the University of Washington, Dr. Davidson works to understand how and why earthworms house bacteria within their kidney-like organs. These bacteria may offer new solutions to nitrogen conservation and treatments for fungal diseases. Other areas of research include bioremediation and waste treatment using vermicomposting.
Seana received her BA in Biology from the University of Oregon and her PhD in Marine Biology from Scripps Institute of Oceanography.
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