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[Ultrastructural observation of E. coli K12 treated with antibacterial peptide CM4]
1State key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433.
Abstract:
The effect of antibacterial peptide CM4 of Bombyx mori against E. coli K12 was investigated using scanning electron microscopy(SEM) and transmission electron microscopy (TEM). The ultrastructural changes of E. coli K12 were observed by the challenge of the purified antibacterial peptide CM4. The results showed that the antibacterial peptide caused a series of pathological changes on E. coli. SEM and TEM revealed aggregates of bacteria and SEM revealed wrinkled bacterial surfaces in the early stage. Thereafter, plasmolysis was observed with irregular holes appearing in the two ends of bacteria and the cytoplasmic contents of the cells leaking out. Finally, bacteria became empty vesicles and disintegrated into small fragments subsequently. Comparatively, the bacterial membrane was normal and the bacterial structure remained intact in the control group.
Insights
The antibacterial peptide CM4 from Bombyx mori effectively damages E. coli K12. Microscopic analysis reveals membrane damage, cell content leakage, and bacterial disintegration, confirming its potent antibacterial activity.
Area of Science:
- Biochemistry
- Microbiology
- Cell Biology
Background:
- Antimicrobial peptides (AMPs) are crucial components of innate immunity.
- Bombyx mori (silkworm) produces AMPs with potential therapeutic applications.
- Escherichia coli K12 is a common model organism for studying bacterial responses.
Purpose of the Study:
- To investigate the ultrastructural effects of Bombyx mori antibacterial peptide CM4 on E. coli K12.
- To elucidate the mechanism of antibacterial action at the cellular level.
Main Methods:
- Scanning Electron Microscopy (SEM) for surface morphology.
- Transmission Electron Microscopy (TEM) for internal ultrastructure.
- Exposure of E. coli K12 to purified CM4 peptide.
Main Results:
- CM4 induced bacterial aggregation and surface wrinkling in E. coli K12.
- Observed plasmolysis, formation of holes, and cytoplasmic leakage.
- Bacteria ultimately disintegrated into empty vesicles and fragments.
- Control group showed intact bacterial membranes and structure.
Conclusions:
- Antibacterial peptide CM4 causes significant pathological changes in E. coli K12.
- CM4 disrupts bacterial membrane integrity and leads to cell death.
- These findings highlight CM4's potential as a novel antibacterial agent.