Abstract
Several isolates of Pseudomonas lachrymans showing resistance against dihydrostreptomycin (DHSM) were obtained from naturally infected cucumber leaves. Cellfree systems prepared from these isolates including N-7641 were able to inactivate DHSM, in the presence of disodium adenosine triphosphate. These enzymically inactivated DHSM were regenerated by alkaline phosphatase treatment, and not by phosphodiesterase. Inactivated DHSM was isolated in crystalline form and its chemical structure was elucidated by means of proton magnetic resonance etc. It was found that the hydroxyl group at C-3 position of the N-methyl-L-glucosamine moiety in DHSM was enzymically phosphorylated. From these results, it was concluded that ATP: aminoglycoside 3"-phosphotransferase participated in DHSM-resistance of Pseudomonas lachrymans N-7641.
