本文通过检测原儿茶醛（PC）对阪崎克罗诺肠杆菌的最小抑菌浓度及对生长曲线的影响，分析其抑菌效果；利用场发射扫描电镜，观测PC对阪崎克罗诺肠杆菌细胞形态的影响；利用多种荧光探针检测PC对细菌细胞膜完整性、胞内pH、胞内ATP浓度、膜电位的作用，探明其可能的抑菌机理。结果表明：PC对阪崎肠杆菌的最小抑菌浓度为0.625~1.25 mg/mL，PC使细菌生长速率和最大菌体浓度显著减小。扫描电镜结果表明PC使菌体干瘪皱缩，丧失原本的棒状杆菌形态。同时，浓度为2MIC和4MIC的PC使细胞膜完整性分别降低49.0%和50.7%，使胞内pH由6.87降低为5.67和4.47，使胞内ATP浓度由1.824 μmol/L降低为0.01 μmol/L以下，并且使细菌细胞膜出现去极化。综上所述，PC对阪崎克罗诺肠杆菌有良好的抑制效果，其可能的抑菌机理是影响细胞膜的通透性，原儿茶醛有潜力作为天然抑菌剂在婴幼儿食品或其他食品中使用。

To investigate the antibacterial activity of protocatechualdehyde (PC), the minimum inhibitory concentrations (MICs) of PC against C. sakazakii strains and the effect of PC on C. sakazakii growth curves were determined. The effect of PC on the cell morphology of C. sakazakii was observed under field emission scanning electron microscope. In addition, the impacts of PC on cell membrane integrity, intracellular pH (pHin), intracellular adenosine triphosphate (ATP) concentration and membrane potential were measured using multiple fluorescent probes to elucidate its possible antibacterial mechanism. The results showed that the MICs of PC against C. sakazakii strains ranged from 0.625 to 1.25 mg/mL, and the addition of PC significantly reduced the specific growth rate and the maximum optical density of C. sakazakii. Electronic microscopy observations indicated that C. sakazakii cells exposed to PC had a wrinkled surface and lost the typical structure of Corynebacterium spp. In addition, PC treatments at concentrations of 2MIC and 4MIC reduced cell integrity by 49.0% and 50.7%, respectively, and caused a decrease in pHin of C. sakazakii from 6.87 to 5.67 and 4.47, respectively; the PC treatments reduced the intracellular ATP concentration from 1.824 μmol/L to less than 0.01 μmol/L. In addition, cells treated with PC showed depolarized cell membranes. In conclusion, PC had good antibiotic activity against C. sakazakii, and its possible mechanism of action was to affect the permeability of the cell membrane. PC has the potential to be used as a natural antibacterial agent in infant formula or other foods.

“十二五”国家科技支撑计划项目（2015BAD16B08）；“浙江省植物有害生物防控重点实验室-省部共建国家重点实验室培育基地（2010DS700124-ZM1608）”项目；教育部“新世纪优秀人才支持计划”（NCET- 13-0488）