Symbioses between marine nematodes and sulfur-oxidizing chemoautotrophic bacteria

Autoren:Ott, Jörg; Bright, Monika; Bulgheresi, Silvia
Abstrakt:Over the course of evolutionary history nematodes and sulfur-oxidizing chemoautotrophic bacteria have formed symbiotic relationships in marine sediments on at least two independent occasions. Mouthless worms of the genus Astomonema have endosymbionts which live intracellularly or extracellularly in the gut rudiment of their host. The ultrastructure of the bacteria and the ecology of the symbiosis are strong indications for a chemoautotrophic nature of the microorganisms; the lack of feeding structures in the host suggests a nutritive dependence on the microbes. In the Stilbonematinae, bacteria cover the outside of the body in a characteristic, species-specific pattern. Ultrastructure, incorporation of inorganic carbon and the presence of RuBisCo and key enzymes of sulfide oxidation pathways show the bacteria to be sulfur-oxidizing chemolithoautotrophs. Stable isotope analysis suggests that the worms depend on the bacteria for their nutrition. In turn, they provide the microorganisms with sulfide and oxygen by repeatedly migrating through the chemocline in sheltered sediments.
Anzahl der Seiten:24
Peer reviewed:true
Bibliographische Notiz:Coden: SYMBE Affiliations: Inst. of Ecol. and Conserv. Biology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria Adressen: Ott, J.; Inst. of Ecol. and Conserv. Biology; University of Vienna; Althanstrasse 14 A-1090 Vienna, Austria; email: Import aus Scopus: 2-s2.0-2542427835 12.02.2008: Datenanforderung 2109 (Import Sachbearbeiter)