Molecular diversity in a hydrogen-consuming enrichment culture from the South Pacific gyre

The South Pasific Gyre is known to be the most oligotrophic water body on earth. Due to a low a very low amount of organic carbon sediments and thus oxygen penetrates deeply into the sediment. Hydrogen produced through natural radiation and radiolysis of water was hypothesized to be a major source of energy for sediment microorganisms. During the Knox-02RR cruise in 2007, the first centimetres of this sediment were sampled and oxic slurries were enriched with an over pressure of H2/CO2 (80:20) for 22 months at 4C. Gas was consumed after this incubation suggesting the activity of Knallgas microorganisms. The microbial community was investigated with a 16S rRNA gene libraries and by T-RFLP. Analysis of 16S rRNA gene showed that only the genus Halomonas was found in the enrichment. This was confirmed by T-RFLP using the restriction enzyme EcoRI, HhaI and SacII. Isolation attempts yielded strains that affiliated to Halomonas. Degenerated primers for a hydrogen subunit did not enable the amplification of a hydrogenase gene. These results suggest a utilisation by Halomonas, eventually by a novel hydrogenase system.

ISCED Categories

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0511 - Biology", "0521 - Ecology