研究37 ℃条件下不同浓度纳米和非纳米氧化镁对单核细胞增生李斯特菌的抑制作用,以及低温（4和-18 ℃）对纳米氧化镁抑菌作用的影响，并通过扫描电子显微镜（SEM）观察了37 ℃条件下纳米氧化镁处理前后单核细胞增生李斯特菌细胞形态的变化。结果表明，37 ℃条件下，纳米氧化镁对单核细胞增生李斯特菌的生长具有明显的抑制作用，且抑菌效果随着纳米氧化镁浓度的增加而增大。在中性缓冲溶液中纳米氧化镁仍具有抑菌效果，但同浓度的非纳米氧化镁以及与纳米氧化镁同pH的碱性条件对单核细胞增生李斯特菌均无显著的抑制作用，因而推测纳米氧化镁的纳米材料特性是其抑菌的主要因素。在低温条件下，对照组单核细胞增生李斯特菌在4 ℃条件下能缓慢生长，-18 ℃条件下呈现下降趋势，添加纳米氧化镁后单核细胞增生李斯特菌的生长均受到显著抑制。37 ℃条件下的扫描电镜结果显示，1.5 mg/mL纳米氧化镁处理后单核细胞增生李斯特菌的菌体有所变长。

The antibacterial effects of different concentrations of magnesium oxide (MgO) nanoparticles and non-nano MgO particles on Listeria monocytogenes were investigated in this study. as Additionally, the impact of low temperature (4 and -18 ℃) on the antibacterial effect of MgO nanoparticles was studied. Scanning electron microscopy (SEM) was used to characterize the morphological changes of L. monocytogenes before and after MgO nanoparticle treatment at 37 ℃. The results showed that MgO nanoparticles had strong antibacterial activity against L. monocytogenes at 37 ℃, in a concentration dependent manner. In addition, MgO nanoparticles showed antibacterial effect in a neutral buffer solution, whereas non-nano MgO at the same concentration had almost no antibacterial effect, along with the alkaline condition with the same pH that was used for MgO nanoparticles. Thus, it is speculated that the main antibacterial factors are the nanomaterial properties of MgO nanoparticles. At low temperature, the L. monocytogenes in the control group grew slowly at 4 ℃, with growth showed a downward trend at -18 ℃. The growth rate of L. monocytogenes was significantly inhibited by the addition of MgO nanoparticles at low temperatures. SEM analysis at 37 ℃ showed that L. monocytogenes cells were elongated after treatment with MgO nanoparticles.

国家自然科学基金项目（U1204331）；“十二五”国家科技支撑计划项目(2012BAD37B07，2015BAD16B04)