Mechanisms of tachyplesin I against Escherichia coli

Abstract:

[Objective] The role mechanism of tachyplesin I on Escherichia coli was investigated to provide potential novel antibacterial drugs for treating disease caused by enteropathogenic bacteria. [Methods] Antimicrobial activity for tachyplesin I for Escherichia coli was determined using Oxford cup and micro-broth dilution methods. The combination, distribution and killing process of tachyplesin I against Escherichia coli were observed under laser confocal scanning microscopy. Ultrastructure of tachyplesin I against Escherichia coli was observed under transmission electron microscope. The genomic DNA and RNA binding ability of tachyplesin I was examined by agarose gel retardation electrophoresis in this experiment. [Results] The minimum inhibitory concentration and minimum bactericidal concentration was 5, 20 mg/L, respectively. The results of laser confocal scanning microscopy and transmission electron microscope indicated that tachyplesin I penetrated the cell membrane of Escherichia coli and accumulated in the cytoplasm immediately after being added to the cells. Later, mem- brane damage and cellular content outflow was seen. And tachyplesin I had effect on genomic DNA in a concentration-dependent manner. The low concentrations of tachypesin I (10 mg/L) had no obvious effect on DNA, while the high concentrations of tachypesin I (above or equal to 80 mg/L) could lead to break in genomic DNA. Tachypesin I could combine with genomic DNA and RNA. [Conclusion] The results provide a theoretical basis to further understand sterilization mechanism of tachyplesin I at molecular level.