Transforming Activities and Base Composition of Deoxyribonucleates from Strains of Moraxella and Mima

Fourteen strains of Moraxella and possibly allied organisms were studied: M. liquefaciens, M. bovis, M. nonliquefaciens, oxidase-positive and oxidasenegative strains of Mima polymorpha and Herellea vaginicola. Classical bacteriological characteristics, capacity to undergo genetic transformation (resistance to 500 μg. dihydrostreptomycin/ml.), and DNA base composition were examined. Moraxella nonliquefaciens and Mima polymorpha var. oxidans were transformable (2 strains at frequencies of 1-4%). Attempts to elicit transformation of the remaining organisms were unsuccessful. The ability of DNA preparations from M. polymorpha var. oxidans to elicit high frequencies of transformation of Moraxella nonliquefaciens, and vice versa, indicated their close relationship. Moreover, their DNA base contents were indistinguishable (about 44·4% guanine + cytosine, 6 strains). The G + C contents averaged 43·1% for 3 oxidase-negative Mima polymorpha strains and 39·8% for 2 Herellea vaginicola strains.