Department of Food Science and Technology, Faculty of Agro-Industry, Kasetsart University, Bangkok 10900, Thailand; Center of International Standard Food Safety, Center for Advanced Studies Agriculture and Food, Kasetsart University, Bangkok 10900, Thailand.
Synchrotron Light Research Institute (Public Organization), Nakhon Ratchasima 30000, Thailand.
Int J Biol Macromol. 2019 Aug 15;135:386-393. doi: 10.1016/j.ijbiomac.2019.05.032. Epub 2019 May 6.
The antibacterial mode of action of chitosan using real-time, horizontal attenuated total reflectance, Fourier-transform infrared (HATR-FTIR) spectroscopy and transmission electron microscopy (TEM) was investigated. Listeria innocua was treated with chitosan solution. HATR-FTIR revealed an increased lethality and substantially metabolomics response on cell components. The main changes in FTIR and their 2nd derivative spectra were at 1045 cm (carbohydrates in cell wall). Principal component analysis clearly segregated untreated and treated cells. Loadings plot revealed the functional groups in cell wall, cell membrane, phospholipid and protein regions of spectrum that are responsible for the classification of treated and control spectra. Kinetic traces of the metabolomics change suggested that cell wall and cell membrane seemed to be the initial target of the antimicrobial mechanism of chitosan. In agreement with the TEM images, which showed breakage of cell wall integrity. The cell wall, cell membrane, phospholipids, proteins and nucleic acids of FTIR spectral data recorded during the cell inactivation were shown to be linked to the metabolomics cell response in the lethality rate and structure of the cells. This work clearly showed, using HATR-FTIR spectroscopy, how bacteria can change their metabolomics response substantially during the first 45 min of contact time.
采用实时、水平衰减全反射傅里叶变换红外光谱（HATR-FTIR）和透射电子显微镜（TEM）研究壳聚糖的抗菌作用模式。用壳聚糖溶液处理无害李斯特菌。HATR-FTIR 揭示了细胞成分的致死率和代谢组学响应的显著增加。FTIR 和其二阶导数光谱的主要变化在 1045 cm（细胞壁中的碳水化合物）处。主成分分析清楚地将未处理和处理的细胞分开。负荷图显示了细胞壁、细胞膜、磷脂和蛋白质区域的功能基团，这些基团负责对处理和对照光谱进行分类。代谢组学变化的动力学轨迹表明，细胞壁和细胞膜似乎是壳聚糖抗菌机制的初始靶标。与 TEM 图像一致，这些图像显示细胞壁完整性的破坏。在细胞失活过程中记录的 FTIR 光谱的细胞壁、细胞膜、磷脂、蛋白质和核酸数据表明，与细胞死亡率和细胞结构相关的是细胞代谢组学反应。这项工作清楚地表明，使用 HATR-FTIR 光谱，细菌在接触时间的前 45 分钟内如何能够显著改变其代谢组学响应。
