Abstract
SUMMARY: Several mutants have been isolated from the facultative methylotroph, Methylobacterium organophilum, using either N-methyl-N′-nitro-N-nitrosoguanidine or ultraviolet light as mutagens. One of these isolates, a glutamate auxotroph lacking isocitrate dehydrogenase, has been transformed to prototrophy, using wild-type DNA, at a frequency of 0.5%. Competence and DNA uptake occur only in cultures which are near the end of exponential growth, and maximal transformation requires a DNA concentration of 100 μg ml-1.