Nutritional effects on frequencies of bacterial recombination.

Riley, Monica (University of California, Berkeley) and Arthur B. Pardee. Nutritional effects on frequencies of bacterial recombination. J. Bacteriol. 83:1332-1335. 1962.-The number of recombinant colonies obtained from mated Escherichia coli is highly dependent on the composition of the medium, both during and after mating, and of the agar medium on which the bacteria are plated. Many bacteria appear to participate in mating, but the efficiency with which they carry out subsequent events leading to recombinant colony formation depends on the physiological state of the zygotes and the challenge to which they are subjected on the selective plates. These findings are reminiscent of the factors which influence the frequency of production of mutants from irradiated bacteria, the survival of bacteria irradiated with ultraviolet light, lysogenization by bacteriophage, or transformation by deoxyribonucleic acid. As a practical measure, care must be taken to hold conditions of plating constant to obtain reproducible numbers of recombinant colonies in mating experiments. For instance, traces of nutrients in agar can greatly affect recombination frequencies.