title: Effect of space factors on Escherichia coli B/r cells.
abstract: Stationary phase cells of Escherichia coli B/r were inactivated when they were exposed to high vacuum (10(-6) torr). About 5% of the cells were still able to form a colony after 45 min exposure. Vacuum dried cells (0.5 torr, 120 min) show colony forming ability of 30% or more. They were inactivated to about 5% by further vacuum treatment. Vacuum treated cells showed higher permeability for various cell components. UV irradiated E. coli B/r cells in vacuum showed increased UV sensitivity. DNA-protein cross-links were preferentially formed in a vacuum. To obtain 63% of DNA cross linked with protein required 852 erg mm-2 (D37) of UV irradiation in suspension and only 72 erg mm-2 of UV irradiation in vacuum. The protein components of DNA-protein cross-links were hydrolysed with pronase E and the amino acids directly bonding to DNA were determined. The most important amino acids concerned in DNA-protein cross-links seem to be glycine and alanine, followed by aspartic acid (asparagine), glutamic acid (glutamine) and histidine. The sensitivity to X-rays of stationary phase E. coli B/r cells seems to depend on the remaining gas atmospheric in the vacuum since it varies with different pumping systems.
authors.affiliation: Arbeitsgruppe fur Biophysikalische Weltraumforschung an der Universitat Frankfurt, Frankfurt/Main, FRG.
authors.forename: H
authors.initials: H
authors.lastname: Bucker
authors.forename: R
authors.initials: R
authors.lastname: Facius
authors.forename: G
authors.initials: G
authors.lastname: Reitz
authors.forename: C
authors.initials: C
authors.lastname: Thomas
authors.forename: H
authors.initials: H
authors.lastname: Wollenhaupt
mesh_terms: D000596:Amino Acids / Q000378:metabolism / Q000528:radiation effects; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004926:Escherichia coli / Q000254:growth & development* / Q000502:physiology / Q000528:radiation effects*; D011836:Radiation Tolerance; D014466:Ultraviolet Rays; D014618:Vacuum; D014965:X-Rays
chemical_list: D000596:Amino Acids; D004269:DNA, Bacterial