Oral Session
S4 Ecology and Diversity
January 20, Tuesday
Morning session (09:00 〜 11:50)
S4-01〜S4-08
Chairperson:
Prof. K. O. STETTER
Prof. J. WIEGEL
Afternoon session
Part 1 (13:15〜15:00) Part 2 (15:30〜17:45)
S4-O9〜S4-O13 S4-O14〜S4-O20
Chairperson: Chairperson:
Prof. J.P. MCKINLEY Prof. W. D. GRANT
Prof. A. T. BULL Prof. A. VENTOSA
Novel Isolates and Cultivation Procedures of Hyperthermophiles
Karl O. STETTER*, Siegfried BURGGRAF, Nicole ElS, Christian HORN, Harald HUBER, Rober HUBER, Reinhard RACHEL, and Gertraud RIEGER
Lehrstuhl fur Mikrobiologie, Universitat Regensburg, Universitatsstraβe 31, D-93053 Regensburg, Germany
During the last years, various hyperthermophiles representing enormous phylogenetic diversity have been isolated (1). However, by direct microscopic and molecular inspection, this appears only as the "tip of a hot iceberg". Due to the lack of direct observation of growing cells of hyperthermophiles, important mechanisms like cell division, surface attachment and function of unique structures like "golf clubs" and cannulae remain unclear. Therefore, for further exploration and deeper understanding of these exceptional organisms, novel procedures are required.
From abyssal hot vents we were able to isolate the archaeon Pyrolobus fumarii (2). By its ability to grow at 113℃ it extends our knowledge about the upper temperature border of life. Pyrolobus is a strictly autotrophic nitrate-ammonifier. Similar organisms could have existed already at the primitive Earth. A further archaeal lineage is represented by the newly discovered Igneococcus, a novel marine hydrogen-sulfur autotroph distantly related to Desulfurococcus (3). Two members of a privotal rod-shaped group of Archaea, tentatively named Korarchaeota are under cultivation and investigation in our lab, now (4) and first results will be provided. In order to select active single cells suitable for isolation and cultivation, we have developed a novel method employing a laser microscope in combination with the application of membrane potential active fluorescence dyes (5, 6). Moreover, for cultivation and direct observation at 100℃ at thousand-fold magnification, a novel thermo-microscope has been established by us, recently. It is equipped with phase contrast and high intensity darkfield illumination. First results on Thermoproteus tenax reveal that golf club formation is not involved in cell propagation. In Pyrodictium occultum formation and growth of the cannulae (H. Huber, et al. in preparation) can be directly observed. A novel further method for cultivating hyperthermophilic Archaea that results in very high cell densities and in improved structural preservation of the cells for electron microscopy (7) will be presented. Employing this procedure, cells of Pyrodictium abyssi exhibit abundant ultraflat areas and are connected by huge networks of cannulae.
1. Stetter, K.O. (1996) FEMS Microbiol. Reviews, 18, 149-158.
2. Blochl, E., Rachel, R., Burggraf, S., Hafenbradl, D., Jannasch, H.W., and Stetter, K.O. (1997)
