Novel biocatalysts from extremophiles

During his Ph.D. research Matthias was investigating enzymes from the extremely thermoacidophilic archaeon Picrophilus torridus and potential applications, which might be optimized by these biocatalysts.

The family Picrophilacaea, in the order Thermoplasmales, consists of two different species, namely Picrophilus oshimae and Picrophilus torridus. Both organism are moderate thermoacidophiles and were isolated in 1995 from solfataric hydrothermal areas in Hokkaido, Japan. Thermoacidophiles are defined as organisms growing at pH values < 3 and at temperatures above 50°C and have been found exclusively in two distinct phylogenetic groups within the Euryarchaeota. A striking feature of Picrophilus is the low intracellular pH value (pH 4.6), which is maintained at extracellular pH values ranging from 0.7 to 4 and it can be assumed that Picrophilus spp. possess not only extracellular, but also intracellular, proteins which are stable and active at acidic pH values. In contrast, other acidophiles, like Metallosphaera sedula or Sulfolobus solfataricus, usually maintain a cytoplasmic pH close to neutrality. Therefore, Picrophilaceae represent an excellent model to examine the adaptation to low pH values and increased temperature at the level of i) structure and function of molecules and cellular structures, ii) physiological and metabolic features, and iii) regulation of gene expression. In recent years, newly methods were established, which suggest that life originated in environments similar to the habitat of existing thermoacidophiles. This emphasises how significant an improved understanding of P. torridus is for the improvement of industrial applications and for the academic community.

Matthias presented the results, obtained during his Ph.D. research, on several international meetings in the U.S.A. (Extremophiles 2004) and in Europe (ProkaGen 2005, Bioprocesses 2006, Biocat 2006). and published them in international peer-reviewed journals.

Deinococcus radiodurans

During his first graduate program he joined the research group of Dr. M. J, Daly at USUHS in Bethesda, MD, USA. Matthias examined the extremly radiation resistant bacterium Deinococcus radiodurans.

The extremely radiation resistant vegetative bacterium Deinococcus radiodurans was isolated in 1956 from gamma-irradiated meat. Since then, it has been the subject of research aimed at understanding the genetic mechanisms underlying its resistance phenotype. In addition to being able to survive high doses of acute gamma radiation, the organism can grow under chronic gamma radiation and recover from a range of other DNA damaging conditions including exposure to desiccation, ultraviolet (UV) radiation and chemical genotoxic agents. This remarkable range of resistance has been attributed to efficient DNA repair processes capable of mending hundreds of single- and double-stranded DNA breaks without lethality or induced mutation. These characteristics were the impetus for sequencing the D. radiodurans genome, ongoing development for bioremediation, proteome and whole genome expression analyses. Matthias was particularly interested in the relationships between the genes of D. radiodurans and the organism's extreme radiation resistance, desiccation resistance, and thermotolerance.