反式肉桂醛对阪崎克罗诺肠杆菌抑制作用的研究

Inhibitory Activity of Trans-cinnamaldehyde Against Cronobacter sakazakii

为寻求安全有效的阪崎克罗诺肠杆菌(Cronobacter sakazakii,C.sakazakii)的控制方法,该文探究了植物源化合物反式肉桂醛(Trans-cinnamaldehyde,TC)对C.sakazakii的抑制作用及可能的作用机制。试验检测了TC对C.sakazakii的最小抑菌浓度(MIC)及其对C.sakazakii生长曲线的影响;利用LIVE/DEAD细菌活性检测试剂盒、激光共聚焦显微镜和场发射扫描电镜,重点分析了TC对C.sakazakii细胞膜完整性及细胞形态的影响;通过构建复原婴幼儿配方乳模型检测TC在4℃、25℃和37℃对C.sakazakii的抑制作用,充分考虑了TC的实际应用效果。结果表明:TC对C.sakazakii最小抑菌浓度为0.4~1.0 mg/m L并可有效延长C.sakazakii的生长延滞期;浓度为MIC和2MIC的TC使C.sakazakii细胞膜完整性降低至60%和46%并可使其细胞膜皱缩、菌体干瘪;浓度为0.4%(V/V)的TC可在90 min(25℃)和60 min(37℃)使复原婴幼儿配方乳中C.sakazakii的数量降低至检出限以下。本研究结果表明TC有潜力作为天然的抗菌物质应用于奶粉等食品中,从而有效地预防和减少阪崎克罗诺肠杆菌引起的相关食源性疾病。

In order to find a safe and effective control method for Cronobacter sakazakii（C. sakazakii）, the antimicrobial activity of trans-cinnamaldehyde（TC） against C. sakazakii and its possible mechanism of action were investigated in this study. The minimum inhibitory concentrations（MICs） of TC against C. sakazakii and its effect on growth curve of C. sakazakii were determined. The effects of TC on cell membrane integrity and cell morphology of C. sakazakii were assessed by using LIVE/DEAD Bac Light bacterial activity assay kit, laser scanning confocal microscope and field emission scanning electron microscope. The inhibitory effect of TC on C. sakazakii at 4 ℃, 25 ℃ and 37 ℃ was studied by constructing a reconstituted infant formula model（containing 0%, 0.1%, 0.2% or 0.4% TC）, and the practical effect of TC was fully considered. The results showed that the MICs of TC against C. sakazakii ranged from 0.4 to 1.0 mg/m L and TC could effectively prolong the growth lag phase of C. sakazakii. Compared with control group, the membrane integrity of the C. sakazakii strain treated with TC at MIC and 2 MIC wasdramatically declined to 60% and 46%, respectively. The field emission scanning electron microscope confirmed that the samples treated with TC had more wrinkled surface compared with the smooth surface of the untreated cells TC at 0.4%（V/V） reduced the number of C. sakazakii in the reconstituted infant formula below the detection limit at 25 ℃ for 90 min or at 37 ℃ for 60 min. In conclusion, TC had the potential to be used as a natural antimicrobial substance in foods such as milk powder and could be further used in the food to effectively prevent and reduce related foodborne diseases caused by C. sakazakii.