Deoxymikanolide adversely altered physiology and ultrastructure of Ralstonia solanacearum

Deoxymikanolide (DEO) was isolated from Mikania micrantha Bunge and identified as a novel antibacterial compound previously. However, the mode of antimicrobial mechanism of DEO was not clear but hypothesized to affect the morphology and physiology of Ralstonia solanacearum cells. In this study, we confirmed our hypothesis via transmission electron microscopy (TEM) observation and comprehensive physiological analyses, including electric conductivity, glycan and phosphorus metabolism, activities of antioxidant enzymes (catalase, peroxidase, and superoxide dismutase), intrabacterial reactive oxygen species (ROS), and malondialdehyde (MDA) levels. We found that glycan and phosphorus metabolism, electric conductivity, intracellular ROS and MDA levels of R. solanacearum cells were significantly increased, while the activities of three antioxidant enzymes were significantly inhibited by DEO treatment. Moreover, TEM analysis showed that DEO treatment led to an earlystage of cell shrinkage, intermediate-stages of cytoplasmic damage, and a final-stage of cell disruption. Altogether, our data presented here indicate that DEO could adversely affect the physiology and morphology of R. solanacearum cells and be treated as an alternative antibacterial treatment in the future.

Automated summary

The study confirmed the hypothesis that DEO affects the morphology and physiology of R. solanacearum cells through physiological analyses and TEM observations. Specifically, DEO treatment increased glycan and phosphorus metabolism, electric conductivity, intracellular ROS and MDA levels, while inhibiting the activities of antioxidant enzymes. TEM analysis showed early-stage cell shrinkage, intermediate-stage cytoplasmic damage, and final-stage cell disruption. The data suggest that DEO could be a potential alternative antibacterial treatment in the future.