Space biochemistry Final report

Abstract

During the EURECA mission spores of Bacillus subtilis, conidia of various Aspergillus species, cells of Deinococcus radiodurans, purple membranes of Halobacteria, plasmid pBR322 and small biomolecules have been exposed in the unit ERA to open space conditions, partially also to selected wavelengths of solar UV light. In addition simulation experiments have been performed in the laboratory and the methods for analyzing the molecular causes for the inactivation of microorganisms by opern space conditions have been optimized. It has been found that dormant forms of microorganisms may exhibit half-lives from months to years if exposed to open space in the dark. Ultimately, however, all species become inactivated due to irrevesible damages of chromosomal DNA (especially by formation of DNA-protein cross-links and DNA strand-breaks. Purple membranes, free amino acids and urea were not measurably altered by exposure to space cacuum in the dark. If irradiated in thin layers with high fluences of solar UV light (#propor to#10"8 Joules/m"2), however, significant damages were induced. In constrast, plasmid pBR322 suffered a significant number of DNA strandbreaks, even if exposed to open space conditions in the dark. The effects produced by exposure of microorganisms to open space could be reproduced in the course of the D2 and the Biopan-1 mission. The relative good survival of some species calls for strict observance of COSPAR Planetary Protection Rules. In addition to the 12 publications that appeared or were accepted in the course of the present project, 5 dimploma dissertations and 2 Ph. D. dissertations have been completed. These dissertations, because of their size, are not enclosed. Up to 3 copies of each one can be provided upon request. (orig.)SIGLEAvailable from TIB Hannover: F95B747+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman