The Action of 2, 4-dichlorophenoxyacetic Acid on Bacterium lactis aerogenes (Aerobacter aerogenes)

2, 4-Dichlorophenoxyacetic acid (2, 4-D) had little effect onthe growth of Bacterium lactis aerogenes at concentrations lowerthan 1,000 mg per 1. As the concentration was raised the lagincreased and the growth-rate decreased gradually. Serial subcultureat 5,000 mg per 1 caused an unusual pattern of behaviour. Firstthe lag at 5,000 mg per 1 fell gradually to a low level overabout 25 subcultures; then, although the lag did not increase,growth became gradually slower over a further 91 subcultures.During the first subculture in 5,000 mg per 1 of 2, 4-D, RNA/masswas low throughout, but DNA/mass and protein/mass were neverlower than normal; polysaccharide/mass passed through a maximumand cell size was unaffected. Possible mechanisms for the actionof the drug are discussed in view of the findings that (i) after1,000 generations of growth in drug the fermentative propertiesand the utilization of glucose by the cells were unimpairedand (ii) the concentration of magnesium ions had little effecton the action of 2, 4-D (unlike EDTA).