Diversity and Function of Epibiotic Microbial Communities on the Galatheid Crab, Shinkaia crosnieri

Abstract

The galatheid crab, Shinkaia crosnieri (Decapoda: Galatheidae), forms dense colonies in the Iheya North and Hatoma Knoll deep-sea hydrothermal fields and has numerous setae covered with filamentous epibiotic microorganisms. Molecular phylogenetic analyses revealed that the epibiotic communities in S. crosnieri consisted mainly of yet-uncultivated phylotypes within Epsilonproteobacteria and Gammaproteobacteria in both hydrothermal vent fields. Uptake experiments using ¹³C-labeled tracers clearly demonstrated that both H¹³CO₃⁻ and ¹³CH₄ were assimilated into not only the epibiotic microbial communities associated with the setae, but also the epibiont-free tissue of living S. crosnieri. In addition, the incorporation of H¹³CO₃⁻ into the microbial cells was strongly stimulated by the presence of reduced sulfur compounds but not by H₂. In conclusion, the uptake experiments suggested that sulfur-oxidizing chemolithoautotrophic and methanotrophic production by the epibionts provides the nutrition for S. crosnieri.