title: Continuous enrichment cultures: insights into prokaryotic diversity and metabolic interactions in deep-sea vent chimneys.
abstract: The prokaryotic diversity of culturable thermophilic communities of deep-sea hydrothermal chimneys was analysed using a continuous enrichment culture performed in a gas-lift bioreactor, and compared to classical batch enrichment cultures in vials. Cultures were conducted at 60 degrees C and pH 6.5 using a complex medium containing carbohydrates, peptides and sulphur, and inoculated with a sample of a hydrothermal black chimney collected at the Rainbow field, Mid-Atlantic Ridge, at 2,275 m depth. To assess the relevance of both culture methods, bacterial and archaeal diversity was studied using cloning and sequencing, DGGE, and whole-cell hybridisation of 16S rRNA genes. Sequences of heterotrophic microorganisms belonging to the genera Marinitoga, Thermosipho, Caminicella (Bacteria) and Thermococcus (Archaea) were obtained from both batch and continuous enrichment cultures while sequences of the autotrophic bacterial genera Deferribacter and Thermodesulfatator were only detected in the continuous bioreactor culture. It is presumed that over time constant metabolite exchanges will have occurred in the continuous enrichment culture enabling the development of a more diverse prokaryotic community. In particular, CO(2) and H(2) produced by the heterotrophic population would support the growth of autotrophic populations. Therefore, continuous enrichment culture is a useful technique to grow over time environmentally representative microbial communities and obtain insights into prokaryotic species interactions that play a crucial role in deep hydrothermal environments.
authors.affiliation: Laboratoire de Microbiologie des Environnements Extrêmes, UMR 6197, IFREMER, Centre de Brest, BP 70, 29280, Plouzané, France. anne.postec@erdw.ethz.ch
authors.forename: Anne
authors.initials: A
authors.lastname: Postec
authors.forename: Françoise
authors.initials: F
authors.lastname: Lesongeur
authors.forename: Patricia
authors.initials: P
authors.lastname: Pignet
authors.forename: Bernard
authors.initials: B
authors.lastname: Ollivier
authors.forename: Joël
authors.initials: J
authors.lastname: Querellou
authors.forename: Anne
authors.initials: A
authors.lastname: Godfroy
mesh_terms: D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D001267:Atlantic Ocean; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D001431:Bacteriological Techniques / Q000295:instrumentation* / Q000379:methods; D044822:Biodiversity; D019149:Bioreactors; D002245:Carbon Dioxide / Q000378:metabolism; D016895:Culture Media, Serum-Free / Q000378:metabolism; D019641:DNA, Archaeal / Q000032:analysis; D015723:Gene Library; D006859:Hydrogen / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010802:Phylogeny; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S; D021521:Ribotyping; D012623:Seawater / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors; D014871:Water Microbiology
chemical_list: D016895:Culture Media, Serum-Free; D019641:DNA, Archaeal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D002245:Carbon Dioxide; D006859:Hydrogen