ATTENUATION OF CROWN GALL BACTERIA BY CULTIVATION IN MEDIA CONTAINING GLYCINE

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Abstract
Earlier observations with regard to the action of glycine on the growth and virulence of crown gall bacteria are confirmed and amplified. Glycine in concns. of 0.1% and above inhibited the growth of crown gall organisms and affected the morphology of the cells. Inhibition occurred in both synthetic and natural media, either of which provided abundant growth when glycine was omitted. After continued cultivation of media containing glycine in concns. which suppressed growth, complete loss of virulence invariably resulted with cultures of both single colony and single cell origin. The rate of attenuation, as measured by the number of transfers to render cultures incapable of gall production, was enhanced by utilizing small inocula, by peptone in the medium, and by maintaining a neutral or slightly alkaline reaction. Attenuation did not occur in glycine media adjusted to pH 5.5 or lower, and growth was not inhibited appreciably in this range.