Archaeal and Bacterial Life at the Upper Temperature Border
Stetter, K.O.
University of Regensburg, Lehrstuhl für Mikrobiologie, Universitätstr. 31,
D-93053 Regensburg, Germany
Information about early life on Earth is limited to morphologial evidence of prokaryotic microfossils. Within the 16S rRNA-based universal phylogenetic tree of today’s life, hyperthermophilic (super-heatloving) prokaryotes occupy all the shortest and deepest branches closest to the common rot. By this, they appear as the most primitive organisms known so fa and may still be rather similar to life at the Early Earth. Although no conclusions can be drwan for the orogin of life, the last common ancestor (which had already ribosomal RNA) had most likely been hyperthermophilic. All recent hyperthermophiles grow optimally at temperature between 80 and 113°C. They are found in active sea mounts, abyssal hot vents, terrestrial volcanic hot springs and geothermally heated (water-containing) deep rocks - environments which had existed already at Archean times. Most hyperthermophiles are able to grow chemolithoautotrophically using CO2 as sole carbon source. Therefore, autotrophy appears to be a very ancient feature in the history of life. The energy-yielding reactions in chemolothoautotrophic hyperthermophiles are anaerobic and aerobic (microaerophilic) types of respiration. Hydrogen gas, reduced sulfur and iron compunds may serve as electron donors, while CO2 and oxidized sulfur and nitrogen compounds may function as electron acceptors, which are present within the environment. Based on their requirements of simple substrates and their independence of sunlight, hyperthermophiles could thrive in any water-containing hot environment - even on other planets.
Stetter, K.O. (1996) Hyperthermophilic prokaryotes. FEMS Microbiology Reviews, 18, 149-158.
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Tuesday, April 7 |
09:40 am |