Forney Lab: Sander Heijs

Microbial communities of Mediterranean cold seep sediments
and their relation to methane driven chemoautotrophy

About ten years ago, dome-like structures called ‘mud volcanoes’ (or ‘cold seeps’) found in deep sea environments of the Atlantic, Eastern and Western Pacific oceans, as well as the Mediterranean Sea were found to discharge large quantities of mud, water, methane and hydrogen sulfide into the overlying water. These mud volcanoes are being intensively studied to assess their potential role as a natural source of atmospheric “pollution” since methane is an important greenhouse gas.

Previous studies have shown that communities of higher organisms including tubeworms, bivalves, fish, and shrimps that live in these environments are likely to be sustained through primary production based on the oxidation of methane or hydrogen sulfide by chemosynthetic bacteria. By analogy with hydrothermal vent ecosystems investigators have presumed that life in these environments is sustained by the oxidation of sulfide by chemoautotrophic prokaryotic organisms. However, more recent carbon-isotope measurements done on sediment samples collected from Mediterranean mud-volcanoes indicate that the oxidation of geochemically produced methane, rather than sulfide oxidation, may prove to be the basis of chemoautotrophy in these ecosystems. Since all microorganisms known to grow at the expense of methane require molecular oxygen to do so, and because oxygen is exceedingly limited in these ‘cold seep’ sediments, the possibility exists that methane oxidation may also occur under anoxic conditions.

Work and progress

Selected samples are characterized using molecular microbial ecology techniques in an effort to identify the microbial populations present so that reasonable inferences can be made about their likely physiological role in these environments. During 2000 the microbial community structure of three different carbonate crusts was studied by analysis of 16S rDNA gene clone libraries. These clone libraries were constructed following PCR amplification of bacterial and archaeal 16S rDNA genes present within extracted community DNA. The data obtained indicate that the eubacterial and archaeal communities in all three crusts were complex and differ in terms of the numerically dominant populations that were present. Combining our results with geochemistry and carbon isotope data (co-operation with NIOZ, Texel and University Pierre et Marie Curie, Paris-France) we were able to conclude that the occurrence of anaerobic methane oxidation is a phylogenetically more widespread phenomenon than previously assumed. In addition, attempts were made to enumerate and isolate populations that are representative of specific functional groups of microorganisms involved in the production and consumption of sulfide or methane. Although it was possible to enrich a mixed culture of the numerically dominant sulfate-reducing bacteria from the sediments of an active mud volcano, the ability to utilize methane under anaerobic conditions was not observed. In the future further attempts to culture numerically dominant organisms of different functional groups will be made.

Analyses of bacterial community structure in selected sediment samples, through profiles of terminal restriction fragment length polymorphisms (T-RFLP analyses) of 16S rDNA genes, have shown that the microbial communities found at different depths in the sediment appear to be similar to one another, but that clear differences can also be discerned based on the presence or absence of specific phylotypes in a given community. Currently, the microbial communities from selected samples are characterized by phylogenetic analyses of the eubacterial and archaeal 16S rDNA genes.

Presentations

Jan. 31, 2000
Verwey AIO-meeting, NIOZ, Texel: Microbial communities of Mediterranean cold seep sediments and their relation to methane driven chemoautotrophy.

April 8, 2000
MedMud progress meeting, VU, Amsterdam: Microbial communities of Mediterranean cold seep sediments and their .relation to methane driven chemoautotrophy – preliminary results.

June 9, 2000
Medineth/Medinaut post-cruise meeting, IFREMER, Brest- France:1) Microbial communities of Mediterranean cold seep sediments and their relation to methane driven chemoautotrophy – preliminary results. 2) Microbial community structure of authigenic carbonate crusts.

Aug. 28, 2001
ISME9-congress, Amsterdam- The Netherlands "Microbial community structure of deep sea carbonate crust : Novel archea involved in anaerobic methane oxidation?" Sander HEIJS, G. Aloisi, I. Bouloubassi, L. Forney, R. Pancost, C. Pierre, Jaap Sinninghr Damsté, J. Gottschal and MEDINAUT Shipboard Party. Oral presentation.

Sept. 13, 2001
MedMud progress meeting, Villefranche Sur Mer, France. (Van Gogh funded). Oral presentation of preliminary data.

Sept. 25, 2001
CIESM-congress, Monaco. "Microbial community structure of deep sea carbonate crust : Novel archea involved in anaerobic methane oxidation?" Sander HEIJS, G. Aloisi, I. Bouloubassi, L. Forney, R. Pancost, C. Pierre, Jaap Sinninghr Damsté, J. Gottschal and MEDINAUT Shipboard Party. Oral presentation

Oct. 10, 2001
Second international symposium on deep-sea hydrothermal vent biology, Brest-France. "Microbial community structure of deep sea carbonate crust : Novel archea involved in anaerobic methane oxidation?" Sander HEIJS, G. Aloisi, I. Bouloubassi, L. Forney, R. Pancost, C. Pierre, Jaap Sinninghr Damsté, J. Gottschal and MEDINAUT Shipboard Party. Poster presentation.

Nov. 12, 2002
DNA isolation from deep sea sediments. University of Idaho, Moscow, Idaho, USA (seminar).

Publications

Heijs, S.K., Aloisi, G., Bouloubassi, I, Forney, L.J., Pancost, R.D.,Gottschal, J.C., and Medinaut Shipboard Scientific Party. Archaeal and eubacterial community structure analysis of deep-sea cold seep carbonate crusts in relation to anaerobic methane oxidation (manuscript in preparation).

Josef P. Werne, Tiphaine Zitter, Ralf R. Haese, Giovanni Aloisi, Ioanna Bouloubassi, Sander Heijs, Aline Fiala-Medioni, Richard D. Pancost, Jaap S. Sinninghe Damsté, Gert de Lange, Larry J. Forney, Jan C. Gottschal , Jean-Paul Foucher, Jean Mascle, John Woodside, and the MEDINAUT & MEDINETH Shipboard Scientific Parties. Life at cold seeps: A synthesis of ecological and biogeochemical data from Kazan mud volcano, eastern Mediterranean Sea (submitted).

Aloisi, G., Bouloubassi, I., Heijs, S.K., Pancost, R.D., Pierre, C., Sinninghe Damsté, J.S., Gottschal, J.C., Forney, L.J., Rouchy, J.-M., and Medinaut Shipboard Scientific Party 2002, CH4-consuming microorganisms and the formation of carbonate crusts at cold seeps. EPSL 203, 195-203.

Heijs, S.K., Aloisi, G., Bouloubassi, I, Forney, L.J., Pancost, R.D.,Gottschal, J.C., and Medinaut Shipboard Scientific Party (2001) Microbial community structure of deep sea carbonate crust : Novel archea involved in anaerobic methane oxidation? ISME-9 International Society for Microbial Ecology, Abstract TU.064, p. 144.

Heijs, S.K., Aloisi, G., Bouloubassi, I, Forney, L.J., Pancost, R.D.,Gottschal, J.C., and Medinaut Shipboard Scientific Party (2001) Microbial community structure of deep sea carbonate crust : Novel archea involved in anaerobic methane oxidation? 36th CIESM Congress Proceedings, Abstract, p. 191.

Heijs, S.K., Aloisi, G., Bouloubassi, I, Forney, L.J., Pancost, R.D.,Gottschal, J.C., and Medinaut Shipboard Scientific Party (2001) Microbial community structure of deep sea carbonate crust : Novel archea involved in anaerobic methane oxidation? 2nd International Symposium on Deep-Sea Hydrothermal Vent Biology, Abstract.

MEDINAUT/MEDINETH Shipboard Scientific Parties (Aloisi, G., Asjes, S., Bakker, K., Bakker, M., Charlou, J.-L., De Lange, G., Donval, J.-P., Fiala-Medioni, A., Foucher, J.-P., Haanstra, R., Haese, R., Heijs, S., Henry, P., Huguen, C., Jelsma, B., de Lint, S., van der Maarel, M., Mascle, J., Muzet, S., Nobbe, G., Pancost, R., Pelle, H., Pierre, C., Polman, W., de Senerpont Domis, L., Sibuet, M., van Wijk, T., Woodside, J., Zitter, T.), 2000, Linking Mediterranean brine pools and mud volcanism, Eos, Transactions, American Geophysical Union, 81(51):625, 631-633.