Kinetic Analysis of the Uv-Resistant Transient Stage in Spore Germination of Bacillus Subtilis

Abstract

An extremely UV-resistant stage was found to appear only temporarily in the early phase of germination of B. subtilis spores. Kinetic analysis of the course of germination with special reference to ultraviolet and heat resistance revealed that the germinating spores remain at this transient stage for one to six minutes depending on the condition of germination, and Transient UV-resistant Stage in Spore Germination 281

Role of Water in Ultraviolet-Resistance of Germinating Bacterial Spores

“…The method for sporulation was the same as previously reported (5) except that the temperature of cultivation was 37°. The spores were purified by Urografin density gradient centrifugation (8) modified as follows : To 1 volume of the washed crude spare suspension (containing vegetative cells), 2 volumes of 60% Urografin solution (Urografin 60, Schering A.G., Berlin/Bergkamen) was added and mixed by gentle stirring.…”

“…1. In this experiment, aliquots of spores removed from the germination medium were irradiated immediately after dilution as described previously (5). The maximum survival was observed at about 5 min of germination.…”

“…The Marburg strain of Bacillus subtilis (wild type) was obtained originally from Dr. H. Saito of The Institute of Applied Microbiology, University of Tokyo, and has been maintained in our laboratory for 9 years (2,5,7).…”

Absence of Transient Elevated UV Resistance during Germination of Bacillus subtilis Spores Lacking Small, Acid-Soluble Spore Proteins α and β

“…Surprisingly, when spores germinate they go through a transient stage of extremely high UV resistance, much higher than that of the dormant spore (3,9,13). This stage lasts only 1 to 6 min for individual spores (4). In spores of B. megaterium and B. cereus, this period of high UV resistance is correlated with a low efficiency of formation of spore photoproducts as well as of pyrimidine dimers in DNA (9,13).…”

“…In contrast to these results, the transient UV resistance of germinating B. subtilis spores was suggested to be due to a highly active germination repair system which is specific for pyrimidine dimers (11). However, detailed kinetic analysis of changes in UV resistance during B. subtilis spore germination suggested that the UV-resistant stage in this organism was also accompanied by a period of diminished photoreactivity of spore DNA (3,4).…”