Characterization of possible symbionts in Onychochaeta borincana (Annelida: Glossoscolecidae)

The presence of symbionts in the gut of Onychochaeta borincana has been suggested but they have never been characterized. The intestinal tissue of this species was examined using electron microscopy and microbiological and molecular biology techniques in order to identify the possible gut associated symbiont. Four gram-positive, endospore-forming and β-hemolytic bacterial strains remained adhered to the intestinal wall of these organisms even after intense cleaning. Molecular and physiological characterization proved their similarity with Bacillus genus, which is typically found in soils and has been reported as a possible intestinal symbiont in arthropods. These results were corroborated by SEM, which showed bacilli structures adhered to the intestinal wall. However, results of molecular tests indicate that a low number of microorganisms remained adhered to intestinal wall after intense cleaning.