Cluster Project F4

Genome-geofuel relations

Hydrothermal vents are characterized by extreme physical (e.g., temperature, pressure) and chemical (oxygen content, redox potential, heavy metal concentration) conditions and steep gradients. They harbor characteristic chemolithoautotrophic microbial communities whose composition and genomic potential is determined by the nature and abundance of the vent geofuels and available electron acceptors. The diversity, quantitative composition, and genomic potential of the non-symbiotic microbial communities dwelling at hydrothermal systems can be studied by cultivation-independent molecular techniques, including comparative sequence analysis of rRNA genes, fluorescence in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes (Amann and Fuchs 2008), and metagenome analysis (Meyerdierks and Gloeckner 2010).

Activities within cluster project F4 are fostering the collection of microbial biomass in rocks, sediments and fluids from which high molecular weight environmental DNA can be extracted. The analysis of the samples is based on hypotheses originating from the analysis of the thermodynamics of particular redox reactions. The samples are precharacterized with respect to microbial community composition by comparative 16S rRNA analysis and FISH. Random metagenome sequencing by next generation sequencing techniques, if indicated in combination with the production and screening of high quality large-insert fosmid libraries, is applied to reveal a rather unbiased access to the metabolic capabilities of microbial key players at hydrothermal vents.

First study site in this project part was a shallow hydrothermal vent off Panarea Island (Aeolian Islands, Italy). In collaboration with J. Amend (Washington University, St. Louis, U.S.A.), F. Italiano (University of Palermo, Sicily, Italy) and R. Price (MARUM), sediments, pore waters, and vent fluids were sampled and in situ profiles were determined. Biomarker analysis (F. Schubotz/R. Summons, MIT, USA) is combined with fingerprint analysis, 16S rRNA gene diversity studies, FISH and metagenome analysis to study the diversity and function of benthic microbial communities. Current study sites are deep-sea hydrothermal vent sites at the Menez Gwen on the Mid Atlantic Ridge (MAR), and in the eastern Manus Basin (Papua New Guinea).