Isolation and identification of freshwater bacteria antagonistic to Giardia intestinalis cysts.

We have isolated three freshwater bacterial strains that demonstrate the ability to degrade Giardia intestinalis cysts. These strains have been identified by 16S rRNA sequencing and phylogenetic analysis as belonging to the Flavobacterium columnare clade of the Cytophaga-Flavobacterium group. While the cyst degradation mechanism is unclear, two different effects on the cysts were observed: non-viability and lysis.