M Lassegues

Antibacterial activity of Eisenia fetida andrei coelomic fluid: Evidence, induction, and animal protection

Abstract Coelomic fluid of the earthworm, Eisenia fetida andrei , naturally inhibits the in vitro growth of the two worm pathogen bacteria, Aeromonas hydrophila (Gram-negative) and Bacillus megaterium (Gram-positive). LD 50 values (injected dose causing death of 50% of the worm population) indicated that E. fetida andrei is more susceptible to A. hydrophila (5 × 10 3 living bacteria) than to B. megaterium (5 × 10 5 ). One injection of LD 50 resulted in an increased humoral bacteriostatic activity peaking 4 days after injection. Such enhanced activity totally protected the worms against infestation with 200 to 2000 times the LD 50 dose and persisted for 4 days with A. hydrophila and 11 days with B. megaterium . Secondary response, different from the first one, was obtained on animals reinjected with the LD 50 dose at the time when normal bacteriostatic activity was recovered (respectively 15 and 22 days after the first injection) but not 15 days later.

Evidence of plasma clotting system in earthworms

Abstract A coagulation of Eisenia fetida andrei coelomic fluid occurs spontaneously in vitro. It is due to the conversion of two plasma proteins of MW 40 and 45 kDa in an insoluble fiber clot. A serine protease activity is suspected triggering the coagulation process. A potent enhancement of coagulation is obtained in presence of freeze-dried mucus, normally secreted by epidermal cells. The presence of chloragosomes favors the development of the clot network. Possible roles of clotting in earthworm life conditions are discussed.

Antibacterial activity of Eisenia fetida andrei coelomic fluid: Specificity of the induced activity

Abstract Adult earthworms Eisenia fetida andrei were found to increase their naturally occurring humoral bacteriostatic activity as a response to bacteria injection. Only the two earthworm pathogenic bacteria we tested, Bacillus megaterium (Gram-positive) and Aeromonas hydrophila (Gramnegative), induced this effect. In contrast, injecting earthworms with nonpathogenic bacteria, such as Acinetobacter sp. and Escherichia coli, as well as with sheep and human O erythrocytes or saline and sterile bacteria culture medium, did not modify the normal activity. When induced, the activity did not discriminate between the two pathogenic bacteria.