Spontaneous mutation rates in continuous cultures: the effect of some environmental factors.

The rate of spontaneous mutation from tryptophan auxotrophy to prototrophy has been determined under different growth-limiting and environmental conditions in continuous cultures of Escherichia coli WP2. The growth rate, aeration rate, pH and temperature were found to affect the rate of mutation. In glucose-limited cultures the mutation rate was found to be directly proportional to both the growth rate and the aeration rate. A temperature coefficient of 2 was observed and there was an optimum temperature and pH for mutation.