Skip navigation
SuUB logo
DSpace logo

  • Home
  • Institutions
    • University of Bremen
    • City University of Applied Sciences
    • Bremerhaven University of Applied Sciences
  • Sign on to:
    • My Media
    • Receive email
      updates
    • Edit Account details

Citation link: http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000105718
00010571.pdf
OpenAccess
 
copyright

Phylogenetic and functional characterization of symbiotic bacteria in gutless marine worms (Annelida, Oligochaeta)


File Description SizeFormat
00010571.pdf6.52 MBAdobe PDFView/Open
Other Titles: Phylogenetische und funktionelle Charakterisierung symbiotischer Bakterien in darmlosen Würmern
Authors: Blazejak, Anna 
Supervisor: Dubilier, Nicole
1. Expert: Amann, Rudolf  
2. Expert: Fischer, Ulrich
Abstract: 
Symbioses between chemoautotrophic bacteria and eukaryotic hosts are widespread in marine environments. In most chemosynthetic endosymbioses, only a single, or at most two bacterial phylotypes co-occur within a host species.In this study the phylogenetic and metabolic diversity of bacterial endosymbionts in gutless marine worms (Annelida, Oligochaeta) from different environments was investigated. Almost all host species harbor a gammaproteobacterial sulfur oxidizer indicating the importance of these Gamma 1 symbionts for the nutrition of the gutless oligochaetes. A second gammaproteobacterial symbiont and deltaproteobacterial symbionts were detected in hosts from coastal silicate sediments, while in hosts from calcareous sands alphaproteobacterial symbionts were identified. Spirochetes were found in hosts from both types of sediments. The phylogenetic diversity of the bacterial symbionts mirrors their different metabolic capabilities. The Deltaproteobacteria have been identified as sulfate reducers and the secondary gammaproteobacterial symbionts are hypothesized to be sulfur oxidizers. Key genes involved in oxidative and reductive sulfur metabolism, CO2 fixation via the Calvin-Benson-Bassham (CBB) cycle, and nitrogen metabolism were successfully detected. Based on phylogenetic analyses it was possible to make potential assignments of genes to a respective symbiont.The use of comparative metagenomics gave first insights into the genome of a gutless oligochaete symbiont. A contiguous sequence of 51 kb from a bacterial artificial chromosome insert contained genes involved in significant metabolic pathways for these symbioses such as sulfur oxidation and CO2 fixation via the CBB cycle indicating that this sequence originated from a thioautotrophic symbiont. This study showed that the symbiotic community in marine gutless oligochaetes with at least three and as many as six different symbiotic phylotypes is much more complex than previously assumed. Despite the high phylogenetic diversity, these associations are clearly specific and stable for most phylotypes within a given host species.
Keywords: symbiosis, chemoautotrophic, sulfur oxidizer, sulfate reducer, oligochaeta
Issue Date: 22-Nov-2005
Type: Dissertation
URN: urn:nbn:de:gbv:46-diss000105718
Institution: Universität Bremen 
Faculty: FB2 Biologie/Chemie 
Appears in Collections:Dissertationen

  

Page view(s)

28
checked on Jan 19, 2021

Download(s)

8
checked on Jan 19, 2021

Google ScholarTM

Check


Items in Media are protected by copyright, with all rights reserved, unless otherwise indicated.

Legal notice -Feedback -Data privacy
Media - Extension maintained and optimized by Logo 4SCIENCE