Thesis subject

Producing Biofuels from the Sea

One of the main biogenic sources of methane are sulfate-depleted marine sediments, but hardly anything is known about the microorganisms responsible for anaerobic mineralization of organic matter in such marine environments.

Methane in marine sediments exists as a free gas, dissolved in the pore water, or is contained within methane hydrates. Methane hydrates may contain 3.1 x 10(15) to 7600 x 10(15) grams of carbon, an amount that exceeds all other organic carbon reservoirs on Earth. In marine sediments, sulfate-reducing bacteria use all the products of primary fermentations and oxidize them to CO2. Therefore, fermentation by syntrophic communities is thought to be limited. However, due to sulfate limitation a main part of the organic matter is not mineralized coupled to sulfate reduction. A recent report demonstrates that syntrophic degradation even occurs in sulfate-containing marine sediments and this is consistent with other studies that showed evidence of methanogenesis by CO2 reduction in sediments with high sulfate concentrations. The presence of syntrophic bacteria in marine sediments has been demonstrated using molecular techniques. Syntrophic associations between propionate- or butyrate-degrading bacteria and methanogens contribute to the vast methane reservoirs contained in marine sediments.

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Aim

We aim to study an important, but hitherto, overlooked component of organic matter cycling and methane production in marine sediments.

Practical Approach

Sediments the Baltic Sea have been used for selective enrichments of syntrophic propionate- and butyrate-degrading consortia at varying temperature and salinity. Samples will be taken at regular intervals, and growth of the enrichments will be followed by chemical measurements and biomolecular techniques. Molecular analysis will be done to determine the changes in diversity and activity of syntrophic bacteria and identification of the species via microscopic detection, 16S rRNA PCR, cloning and sequencing.

Techniques and Methods

  • Microbe detection and quantification with Fluorescent in Situ Hybridization, and multiple 16S rRNA detection methods
  • Population dynamics of marine microbial communities
  • Chemical analysis (GC, HPLC, GC-MS)

More information

Project for Msc students with interest in Environmental Microbiology

Supervisor: Derya Ozuolmez

Contact info: derya.ozuolmez@wur.nl

Tel: 0317-486013 Laboratory of Microbiology Microbiology building, room 0014
Duration: 4-6.5 months

Credits: 39 (max.)

This project is mainly designed for an MSc thesis (6 months), yet it is possible to have a short term (4 months) project. This project aims to give students experience with growing cultures in anaerobic conditions, working with different microbial and molecular techniques and data analysis. Please do not hesitate to contact us for further information.