Ancient thermophiles in the 21st century– a new era for heat loving microbes
Microorganisms with high growth temperature optima (Thermophiles, TOPT >45°C) are considered ancient organisms, and the first cellular life on Earth may actually have been thermophilic. In the second half of the last century, many Thermophiles were isolated and physiologically characterized. Then, especially their enzymes attracted interest of scientist, since they were relatively easy to purify, and they offered new opportunities: Understanding structure and function of enzymes – and applying them in biotechnology.
Since a about decade, the development of genetic systems for thermophilic microorganisms led to more detailed understanding of their physiology. Moreover, it now enables the utilization of Thermophiles as whole-cell biocatalysts. Physiological properties of Thermophiles that utilize lignocellulose-derived sugars or synthesis gas (H2, CO, CO2) as substrates will be discussed, in the light of their genetic engineering towards application. In particular, the bioenergetics of H2+CO2 utilization by the most thermophilic acetogen, Thermoanaerobacter kivui, TOPT 66°C), as well as alcohol production by a modified strain of the hyperthermophilic archaeon Pyrococcus furiosus (TOPT 100°C) and by Thermoanaerobacter species will be presented. Finally, it will be discussed how genetics in Thermophiles may reveal how (mesophilic) Life on Earth evolved.