Chair of Food Chemistry , Technische Universität Dresden , D-01062 Dresden , Germany.
Institut für Medizinische Mikrobiologie und Hygiene, Medizinische Fakultät Carl Gustav Carus , Technische Universität Dresden , Fetscherstraße 74 , 01307 Dresden , Germany.
J Agric Food Chem. 2019 Feb 20;67(7):1963-1972. doi: 10.1021/acs.jafc.8b06748. Epub 2019 Feb 12.
N-ε-Carboxymethyllysine (CML) is formed during glycation reactions (synonym, Maillard reaction). CML is degraded by the human colonic microbiota, but nothing is known about the formation of particular metabolites. In the present study, six probiotic E. coli strains were incubated with CML in the presence or absence of oxygen in either minimal or nutrient-rich medium. CML was degraded by all strains only in the presence of oxygen. HPLC-MS/MS was applied for identification of metabolites of CML. For the first time, three bacterial metabolites of CML have been identified, namely N-carboxymethylcadaverine (CM-CAD), N-carboxymethylaminopentanoic acid (CM-APA), and the N-carboxymethyl-Δ-piperideinium ion. During 48 h of incubation of CML with five different E. coli strains in minimal medium in the presence of oxygen, 37-66% of CML was degraded, while CM-CAD (1.5-8.4% of the initial CML dose) and CM-APA (0.04-0.11% of the initial CML dose) were formed linearly. Formation of the metabolites is enhanced when dipeptide-bound CML is applied, indicating that transport phenomena may play an important role in the "handling" of the compound by microorganisms.
N-ε-羧甲基赖氨酸（CML）是在糖化反应（同义词，美拉德反应）过程中形成的。CML 被人体结肠微生物群降解，但对于特定代谢物的形成知之甚少。在本研究中，将六种益生菌大肠杆菌菌株在有氧或无氧条件下分别在最小或营养丰富的培养基中与 CML 孵育。所有菌株仅在有氧条件下才能降解 CML。HPLC-MS/MS 用于鉴定 CML 的代谢物。首次鉴定了 CML 的三种细菌代谢物，即 N-羧甲基尸胺（CM-CAD）、N-羧甲基氨基戊酸（CM-APA）和 N-羧甲基-Δ-哌啶酮离子。在有氧条件下，将 CML 与五种不同的大肠杆菌菌株在最小培养基中孵育 48 小时，CML 降解率为 37-66%，而 CM-CAD（初始 CML 剂量的 1.5-8.4%）和 CM-APA（初始 CML 剂量的 0.04-0.11%）则呈线性形成。当应用二肽结合的 CML 时，代谢物的形成得到增强，这表明运输现象可能在微生物“处理”化合物中发挥重要作用。
