Download Testing for Chemotaxis in Earthworm Bacterial Symbiont

Testing for Chemotaxis in Earthworm Bacterial Symbiont
Eduardo Rojas1, Adrian Diaz1,2, Seana K. Davidson, PhD2
1
UW GenOM Project, 2Department of Environmental Engineering
University of Washington, Seattle, Washington
Abstract
The earthworm Eisenia fetida, commonly known as the “Red Wiggler,” is a widely used
worm in composting. This species of worm is a host of a mutually beneficial relationship with
many species of bacterium that colonize in the kidney like structures of E. fetida called
nephridia. The nephridia host three bacterial species, Microbacteriaceae, Flexibacteriaceae, and
Verminephrobacter, which colonize through vertical transmission in the albumin of the egg
capsule. V. eiseniae is grown in culture in the lab; the remaining species are still difficult to
grow. Previous work has shown that the V. eiseniae colonizes into the nephridia through the use
of both a flagella and type IV pili. This current project seeks to test for motility through
chemotaxis and find out the chemoattractants used to direct bacteria into nephridia during
development. Chemotaxis of V. eiseniae will be analyzed by using a 6 and 12 well chemotaxis
assay in which the bacteria cells (mutant or wild type) are placed a distance from the attractants
being tested to create a concentration gradient. The movement of the bacterial bodies will then be
analyzed and significant motility patterns in a direction will prove chemotaxis for that substance.
Both ammonia and pyruvate are thought to be likely attractants because ammonia’s
concentration in the nephridia where the bacteria colonize and pyruvate is used utilized in the
growth medium of the bacterial cells. The project will assist in understanding bacterial
colonization in motility in symbiotic relationships as well as pathogenic bacteria.