Co-existence of opportunistic symbiont and its metabolic relationship with the tubeworm, Lamellibrachia satsuma

Abstract

Although attempts have been made to reveal the relationships between endosymbiont and tubeworm, little is known about the acquisition and coexistence of multiple symbiotic members in vestimentiferan. To reveal this, we studied on Lamellibrachia satsuma, one of the common members of faunal communities in the Kagosima Bay, nourished by chemoautotrophic endosymbionts growing in a specialized tissue called the trophosome. Two different samples of L. satsuma from different locations of the seep were studied. Library was constructed from the DNA extracted from trophosome and sequenced using Illumina HiSeq 2000 platform. Metagenomic sequences were annotated using MG-RAST pipelines and comparative analysis carried out by STAMP software. Based on 16S rRNA gene fragments recovered from metagenomic sequences and 16S rRNA gene cloning, it was reported that the tubeworm commonly harbor γ-proteobacteria closely related to endosymbiont of genus Lamellibrachia and Escarpia regardless of different locations, however we found the presence of e-proteobacteria in one sample, closely related to ectosymbiont of Rimicaris exoculata. These symbionts contain all genes essential for sulfur-oxidizing metabolism through the cytoplasmic enzymes (AprA/AprB) and periplasmic sulfite oxidase enzyme complex (Sox). Two different carbon fixation pathways, the Calvin cycle as well as rTCA cycle also found, as has been reported in the endosymbiont ofchia satsuma, one of the common members of faunal communities in the Kagosima Bay, nourished by chemoautotrophic endosymbionts growing in a specialized tissue called the trophosome. Two different samples of L. satsuma from different locations of the seep were studied. Library was constructed from the DNA extracted from trophosome and sequenced using Illumina HiSeq 2000 platform. Metagenomic sequences were annotated using MG-RAST pipelines and comparative analysis carried out by STAMP software. Based on 16S rRNA gene fragments recovered from metagenomic sequences and 16S rRNA gene cloning, it was reported that the tubeworm commonly harbor γ-proteobacteria closely related to endosymbiont of genus Lamellibrachia and Escarpia regardless of different locations, however we found the presence of e-proteobacteria in one sample, closely related to ectosymbiont of Rimicaris exoculata. These symbionts contain all genes essential for sulfur-oxidizing metabolism through the cytoplasmic enzymes (AprA/AprB) and periplasmic sulfite oxidase enzyme complex (Sox). Two different carbon fixation pathways, the Calvin cycle as well as rTCA cycle also found, as has been reported in the endosymbiont of