Evidence for chemoautotrophic symbiosis in a Mediterranean cold seep clam (Bivalvia: Lucinidae): comparative sequence analysis of bacterial 16S rRNA, APS reductase and RubisCO genes

• Published in: FEMS microbiology ecology 2007-01, Vol.59 (1), p.64-70
• Main Authors: Duperron, Sébastien, Fiala-Médioni, Aline, Caprais, Jean-Claude, Olu, Karine, Sibuet, Myriam
• Format: Article
• Language: English
• Subjects: Animals; Autotrophy; Bacteria; Bacteria - enzymology; Bacteria - genetics; Bacteria - growth & development; Bacteriology; Biological and medical sciences; Bivalvia; Bivalvia - genetics; Bivalvia - microbiology; Chemoautotrophic Growth; cold seeps; Cores; Deep sea; Deep sea environments; eastern Mediterranean; Ecology; Electron micrographs; Fundamental and applied biological sciences. Psychology; Gammaproteobacteria - enzymology; Gammaproteobacteria - genetics; Gene sequencing; Gills; Hypotheses; Lucinidae; Lucinoma; Lucinoma kazani; Marine; Mediterranean Region; Microbiology; Miscellaneous; Nutrition; Ocean, Atmosphere; Oxidation; Oxidoreductases Acting on Sulfur Group Donors - chemistry; Oxidoreductases Acting on Sulfur Group Donors - genetics; Oxidoreductases Acting on Sulfur Group Donors - metabolism; Oxygenase; Phylogeny; Reductase; Reductases; Ribulose-1,5-bisphosphate; Ribulose-bisphosphate carboxylase; Ribulose-Bisphosphate Carboxylase - chemistry; Ribulose-Bisphosphate Carboxylase - genetics; RNA, Ribosomal, 16S - genetics; rRNA 16S; Sciences of the Universe; Sequence Analysis; Spirochaeta - enzymology; Spirochaeta - genetics; Spirochetes; Sulfides; sulphide‐oxidizing bacteria; Symbiosis; Vacuoles
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2006.00194.x

Abstract Symbioses between lucinid clams (Bivalvia: Lucinidae) and autotrophic sulphide-oxidizing bacteria have mainly been studied in shallow coastal species, and information regarding deep-sea species is scarce. Here we study the symbiosis of a clam, resembling Lucinoma kazani, which was recently collected in sediment cores from new cold-seep sites in the vicinity of the Nile deep-sea fan, eastern Mediterranean, at depths ranging from 507 to 1691 m. A dominant bacterial phylotype, related to the sulphide-oxidizing symbiont of Lucinoma aequizonata, was identified in gill tissue by comparative 16S rRNA gene sequence analysis. A second phylotype, related to spirochete sequences, was identified twice in a library of 94 clones. Comparative analyses of gene sequences encoding the APS reductase α subunit and ribulose-1,5-bisphosphate carboxylase oxygenase support the hypothesis that the dominant symbiont can perform sulphide oxidation and autotrophy. Transmission electron micrographs of gills confirmed the dominance of sulphide-oxidizing bacteria, which display typical vacuoles, and δ13C values measured in gill and foot tissue further support the hypothesis for a chemoautotrophic-sourced host carbon nutrition.