Stimulation by X-Radiation of Enzyme Induction and Growth in Escherichia coli

• Published in: Proceedings of the Royal Society of London. Series B, Containing papers of a biological character Vol. 150; no. 941; p. 539
• Main Authors: LASER, H, THORNLEY, M J
• Format: Journal Article
• Language: English
• Published: England The Royal Society 01.09.1959
• Subjects: AGE; AMINO ACIDS; AMMONIUM COMPOUNDS; ANTIBIOTICS; BACTERIA; CARBON; CHLORAMPHENICOL; CHLORIDES; CONTROL; DECOMPOSITION; Enzyme Induction; ENZYMES; ESCHERICHIA COLI; GLUCOSE; GLUTAMIC ACID; IRRADIATION; LIQUIDS; MALTOSE; MEASURED VALUES; MICROORGANISMS; MITOSIS; NITROGEN; NUMERICALS; ORGANIC NITROGEN COMPOUNDS; OXIDATION; OXYGEN; PROTEINS; QUANTITY RATIO; RADIATION DOSES; RADIATION EFFECTS; RADIOLOGY AND NUCLEAR MEDICINE; REPRODUCTION; SALTS; SAMPLING; SUGARS; SUSPENSIONS; ULTRASONICS; USES; VARIATIONS; X RADIATION; X-Rays; RADIATION EFFECTS/experimental
• ISSN: 0962-8452; 0950-1193; 1471-2954
• DOI: 10.1098/rspb.1959.0041

Escherichia coli B has been grown in a liquid medium containing, besides inorganic salts, glucose and ammonium chloride as sole sources of carbon and nitrogen. The micro-organisms do not grow if maltose is substituted for glucose. Similarly, washed suspensions of Esch. coli which oxidize glucose vigorously have an insignificant $\text{O}_{2}\text{-uptake}$ with maltose. However, maltose is utilized for growth if $\text{NH}_{4}\text{Cl}$ is replaced by glutamic acid. Apparently the bacteria cannot form the enzyme needed to utilize maltose from their existing protein equipment but can if given a suitable organic nitrogen source. X-radiation of 4-8 kr (190 kVp, 10 mA, dose rate 8 kr/min) changes these conditions fundamentally: (i) Washed suspensions of irradiated Esch. coli oxidize glucose as fast as controls, but--unlike the controls--develop an increasing respiration in presence of maltose, the maximal rate (after 4 to 8 kr) being attained within 3 h and approaching that for glucose. (ii) This response to maltose is suppressed by chloramphenicol. (iii) Micro-organisms viable after irradiation can grow on maltose in the liquid medium with $\text{NH}_{4}\text{Cl}$, although slowly. (iv) The viable irradiated micro-organisms multiply with maltose and glutamate much faster than unirradiated controls for most of the logarithmic growth phase. This has been confirmed by turbidity measurements and plate counts. (v) The response to maltose is lost on incubation of the bacteria with glucose and $\text{NH}_{4}\text{Cl}$. (vi) Both controls and irradiated Esch. coli contain maltase. This has been demonstrated with ultrasonically disintegrated bacteria where the addition of maltose and glucose oxidase (notatin) caused an $\text{O}_{2}$-uptake at equal rates in both samples. These results and further evidence justify the conclusion that the observed irradiation effects are due to the induction of permease for maltose in irradiated micro-organisms.