Spirochaeta sp. ELBA Genome sequencing. Spirochaeta sp. ELBA

The gutless marine worm O. algarvensis harbors five bacterial endosymbionts that have taken over the functions of its reduced digestive and excretory system. In 2006, Woyke et al. (Nature 443, 950-955) sequenced the symbiotic metagenome of this worm, thereby revealing novel insights into how the symbionts a) feed their host using autotrophic pathways for CO2 fixation, b) recycle their host?s waste products and c) interact with each other in a syntrophic exchange of oxidized and reduced sulfur compounds, thus enabling the symbiosis to thrive under energy limited conditions. Of the five symbionts present in O. algarvensis, Woyke et al. (2006) succeeded in characterizing four, but for the spirochetal symbionts no contigs could be assembled, so that its physiology and role in the symbiosis remains unknown. Based on the physiology of other members of the genus to which the symbiont belongs, the Spirochaeta, we hypothesize that it is a facultative anaerobe that ferments carbohydrates including cellobiose and sucrose to acetate, ethanol, formate, CO2 and hydrogen.