Atmungsgrößen von Escherichia coli B/r and B s 1 und der Einfluß hoher UV-Dosen

Abstract

Two very different radiation sensitive strains of Escherichia coli (B/r and Bs1) showed only small differences of their rest metabolism. A significant distinction is to be seen some hours after separation of the bacteria from the nutrient substrate. There is a slow decrease of respiration intensity of the B/r strain. The nucleoside adenosine which in buffer solution with glucose influenced only the B/r cells increased the respiration rate of this strain on the same level as the Bs1 cells. Without glucose (endogenous respiration), the oxygen consumption of both strains is very small, but can be increased on the level of exogenous respiration by application of adenosine (5 × 10−3 M). The small endogenous respiration is not decreased by high UV-doses; the glucose respiration after 80000 erg. mm−2 falls to about 50% of the control. Adenosine can diminish this decline. These and other experiments showed an increase in the resistance to UV irradiation in the folllowing sequence: growth respiration in complete medium, glucose respiration in phosphate buffer, and endogenous respiration; the activity of metabolism falls in the same sequence. The different radiosensitivity of both bacterial strains may not be understood by their rest metabolism, which is very similar in both cases, except one suggests a multiplication of the small differences during the growth metabolism.