Reciprocal Genetic Transformation Between Neisseria catarrhalis and Moraxella nonliquefaciens

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Abstract
Deoxyribonucleate (DNA) preparations from Moraxella nonliquefaciens elicited genetic transformation of Neisseria catarrhalis recipient cells, and vice versa. The frequency was low (0.0005% transformation for the most reactive of six strains), as might be expected of an interaction between two organisms as dissimilar as a rod and a coccus. Evidence that the hereditary change (attainment by susceptible cells of resistance to 500 [mu]g. dihydrostreptomycin/ml.) was due to transformation was provided by the typical time course of the reaction, the typical linear response to decreasing concentrations of DNA below 0.1 [mu]g./ml., and by tests of transforming activity of DNA preparations extracted from 11 dihydrostreptomycin-resistant (str-r) strains which arose by intergeneric transformation. These DNAs had relatively high transforming activity for recipient strains of both species. Thus, the str-r region of the transforming DNA molecule from a trans-formant strain of M. nonliquefacients was recognized and genetically integrated by populations of N. catarrhalis recipient cells at frequencies as much as 10,000 times higher than those of DNA from strains of M. nonliquefaciens str-r (derived by spontaneous mutation). The results with DNA preparations from particular transformants are interpreted as indicating that the length of a DNA nucleotlde sequence which is integrated by a cell during str-r transformation may differ for different cells of the same treated population.