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RESEARCH PRODUCT

Identification of the ectosymbiotic bacteria of Mixotricha paradoxa involved in movement symbiosis

subject

description

Mixotricha paradoxa, a trichomonad from the hindgut of the Australian termite Mastotermes darwiniensis Froggatt, is a rare example of a movement symbiosis between eukaryotic and prokaryotic microorganisms. The surface of Mixotricha paradoxa is covered with spirochaetes and a rod-shaped bacterium. The four flagella at the anterior end seem only to alter the direction of movement, while the ectosymbiotic spirochaetes propel the flagellate cells. Based on a 16S rDNA sequence analysis after a semi-specific PCR, and subsequent fluorescence in situ hybridization applying helper oligonucleotides and a denaturing step of the 16S rRNA, three different spirochaete clones could be clearly identified on the surface of the protozoal cells. They belonged to the Treponema cluster. The rod shaped bacterium showed highest 16S rDNA sequence similarity to species related to Bacteroides. Due to its low phylogenetic relationship to its nearest relatives in the database, it should represent a so far undescribed species.