TRANSFORMATION OF NEISSERIA MENINGITIDIS BY DEOXYRIBONUCLEATES FROM CELLS AND FROM CULTURE SLIME

Abstract

Highly polymerized deoxyribonucleate (DNA) is a component of the slime that accumulates in some cultures of N. meningitidis as viability declines. A quantitative transformation method was developed to investigate the genetic activity of such extracellular DNA. Extracellular DNA was separated by ethanol precipitation from the supernatant broth of centrifuged slimy cultures of a streptomycin-resistant strain. Intra-cellular DNA was extracted from detergent-lysed cells. Solutions of partially purified DNA preparations from the 2 sources exhibited similar transforming activities. Crude culture slime, in dilutions as high as 1:25, elicited about the same number of transformants as were obtained with DNA preparations at a concentration of 5 [mu]g DNA per ml. The possibility was discussed that natural variation of meningococci. and perhaps of other bacteria, may be enhanced through the agency of transformation by slime layer DNA.