Chair of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Poland; Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, 7 Gagarina Str., 87-100 Torun, Poland.
Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, 7 Gagarina Str., 87-100 Torun, Poland.
J Chromatogr A. 2021 Aug 30;1652:462127. doi: 10.1016/j.chroma.2021.462127. Epub 2021 Mar 30.
In this work, the molecular mechanism of Lactobacillus paracasei bio-colloid clumping under divalent metal ions treatment such as zinc, copper and magnesium at constant concentrations was studied. The work involved experimental (electrophoretic - capillary electrophoresis in pseudo-isotachophoresis mode, spectroscopic and spectrometric - FT-IR and MALDI-TOF-MS, microscopic - fluorescent microscopy, and flow cytometry) and theoretical (DFT calculations of model complex systems) characterization. Electrophoretic results have pointed out the formation of aggregates under the Zn and Cu modification, whereas the use of the Mg allowed focusing the zone of L. paracasei biocolloid. According to the FT-IR analysis, the major functional groups involved in the aggregation are deprotonated carboxyl and amide groups derived from the bacterial surface structure. Nature of the divalent metal ions was shown to be one of the key factors influencing the bacterial aggregation process. Proteomic analysis showed that surface modification had a considerable impact on bacteria molecular profiles and protein expression, mainly linked to the activation of carbohydrate and nucleotides metabolism as well with the transcription regulation and membrane transport. Density-functional theory (DFT) calculations of modeled Cu, Mg and Zn coordination complexes support the interaction between the divalent metal ions and bacterial proteins. Consequently, the possible mechanism of the aggregation phenomenon was proposed. Therefore, this comprehensive study could be further applied in evaluation of biocolloid aggregation under different types of metal ions.
本工作研究了在恒定浓度的二价金属离子（如锌、铜和镁）作用下，副干酪乳杆菌生物胶体聚集的分子机制。该工作涉及实验（电泳-伪等速电泳模式下的毛细管电泳、光谱和分光光度法-FT-IR 和 MALDI-TOF-MS、显微镜-荧光显微镜和流式细胞术）和理论（模型复杂体系的 DFT 计算）表征。电泳结果表明，Zn 和 Cu 修饰下会形成聚集体，而使用 Mg 则可以聚焦 L. paracasei 生物胶体区带。根据 FT-IR 分析，参与聚集的主要官能团是来自细菌表面结构的去质子化羧基和酰胺基。二价金属离子的性质被证明是影响细菌聚集过程的关键因素之一。蛋白质组学分析表明，表面修饰对细菌分子谱和蛋白质表达有很大影响，主要与碳水化合物和核苷酸代谢的激活以及转录调控和膜转运有关。模型化 Cu、Mg 和 Zn 配位配合物的密度泛函理论（DFT）计算支持二价金属离子与细菌蛋白之间的相互作用。因此，提出了聚集现象的可能机制。因此，这项综合研究可以进一步应用于评估不同类型金属离子下生物胶体的聚集。
