蓝光对阪崎肠杆菌的杀菌及机制研究

Inactivation of Cronobacter sakazakii by Blue Light and the Mechanism

摘要:

本文以食源性致病菌阪崎肠杆菌为对象，研究了医学领域抗细菌感染蓝光的杀菌作用，并首次对其杀菌机制进行了探究。结果表明，当蓝光剂量大于30 J/cm2时，对阪崎肠杆菌具有显著杀菌作用，照射剂量达240 J/cm2时，杀菌率超过8 log 10 CFU。亚致死剂量（0~30 J/cm2）蓝光照射下，单线态氧（1O2）探针SOSG开始出现绿色荧光信号，显示细胞内1O2涌现并造成细胞外壁微小孔洞；活性氧物质（ROS）也迅速产生并逐渐增大至5 a.u.；随后脂质氧化标志物丙二醛（MDA）逐渐增加，显示细胞内产生脂质氧化。上述胞内物质变化导致细胞外膜受损，30 J/cm2蓝光下细胞外膜渗透性增加了48.96%；此外脂肪酰基谱测定揭示，不饱和脂肪酸C18:2，C16:1和C18:1含量减少并逐渐消失，很可能是细胞外膜损伤的重要原因之一。本研究确证了蓝光下细菌胞内1O2、ROS及脂质氧化物的动态变化，更重要是的，揭示了细胞外膜损伤是蓝光杀菌的重要方式之一，因为细菌脂质尤其是不饱和脂肪酸是蓝光杀菌重要靶标，本研究将有助于蓝光杀菌机制的深入探究。

Abstract:

Blue light (BL) had been employed in medicine recently to inactivate bacteria, while its mechanism needed to be investigated. Thus, this work conducted herein examined the bactericidal effect of BL on the food borne pathogen Cronobacter sakazakii, and the underlying mechanism. The results showed that BL above 30 J/cm2 exhibited an efficient bactericidal effect against C. sakazakii, and an inactivation rate above 8 log10 CFU was achieved under 240 J/cm2. Under the sublethal BL dose, singlet oxygen (1O2) and reactive oxygen species (ROS) were rapidly produced and gradually increased, followed by the emergence of malondialdehyde (MDA), indicating lipid oxidation in cells. Moreover, the permeability of the outer membrane of cell increased by 48.96% at 30 J/cm2, indicating injury to cell membranes. Results of fatty acid spectra showed that the contents of unsaturated fatty acids C18:2, C16:1 and C18:1 decreased and disappeared. This work confirmed at the first time the dynamic change of intracellular 1O2、ROS and MDA, and especially, revealed that damage on cell outer membrane was one the inactivation means of BL, because bacterial lipids, especially unsaturated fatty acids, are important targets for BL. These results will contribute to the study of the mechanism of blue-light sterilization.