摘要
As a novel non-thermal sterilization method, pulsed light (PL) has been widely employed in the food industry to control microbial contamination. However, the antimicrobial mechanism underlying PL treatment remains poorly understood. This study investigated the antimicrobial mechanism of PL against Escherichia coli , focusing on PL‑induced alterations in cellular morphology, ultrastructure, biochemical composition, intracellular leakage, metabolic activity, and membrane integrity. Results from scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that PL treatment severely disrupted the morphology and cellular integrity of E. coli , inducing numerous micro-damages on the bacterial surface and causing alterations in surface mechanical properties. Fourier transform infrared spectroscopy (FT-IR) indicated significant changes in the membrane fatty acids and chemical structure of E. coli in PL-treated samples. Confocal laser scanning microscopy (CLSM) demonstrated severe morphological damage to PL-treated cells, which compromised cell membrane integrity and led to the leakage of intracellular DNA and proteins. Furthermore, PL treatment inhibited energy metabolism and biosynthesis, resulting in a sharp decline in metabolic activity. Concurrently, PL treatment induced a dramatic increase in intracellular reactive oxygen species (ROS) levels, thereby contributing to structural disruption and metabolic collapse from both internal and external pathways, ultimately accelerating cell death. Finally, PL exhibited remarkable sterilization efficacy in the inactivation of E. coli , PL (1.36 J/cm 2 of cumulative fluence) achieved a log reduction greater than 6 in bacterial (10⁷ CFU/mL) inactivation experiment. In the analysis of sterilization in different spectral bands of PL, we found that the UVC band contributes most significantly to bacterial inactivation. These results indicate that PL is an effective technical method for inactivating E. coli .
危险品化学品经营许可证（带存储）