Mechanism of action of neomycin on Erwinia carotovora subsp. carotovora

Abstract Neomycin is an aminoglycoside antibiotic, which has long been widely used in livestock animals. Thus far, there has been no description that neomycin had antibacterial activity against plant pathogenic bacteria. This research focused on the bacteriostatic action and mechanism of neomycin on plant pathogenic bacteria. Antibacterial experiments indicated that the minimum inhibition concentration (MIC) of neomycin against Erwinia carotovora subsp. carotovora was 0.004 g/L. Experiments have been carried out to confirm a significant positive correlation between the concentration of neomycin and the bacteriostatic activity of neomycin. Moreover, electron microscopy revealed that many cavities were formed in the cells, and the cytoplasm was concentrated. The bacterial membrane was damaged and there was leakage. Finally, the cell lysed. In SDS–PAGE experiments, after treatment with neomycin, the electrophoresis bands appeared shallow. After treatment with neomycin for 6 h, the number of bacteria in Phase I (DNA preparatory period) increased from 65.13% to 82.54% and Phase R (DNA copy period) was reduced significantly from 34.87% to 17.40%. Our current findings indicated that neomycin presented significant antimicrobial activity on plant pathogenic bacteria; the bacteriostatic mechanism of neomycin was such that neomycin inhibited the synthesis of proteins associated with growth and cleavage of bacteria, thus blocking cell division and growth.