Introduction

Multivalent antimicrobial dendrimers are an exciting new system that is being developed to address the growing problem of drug resistant bacteria. Nuclear Magnetic Resonance (NMR) metabolomics is a quantitative and reproducible method for the determination of bacterial response to environmental stressors and for visualization of perturbations to biochemical pathways.

Objectives

NMR metabolomics is used to elucidate metabolite differences between wild type and antimicrobially mutated Escherichia coli (E. coli) samples.

Methods

Proton (¹H) NMR hydrophilic metabolite analysis was conducted on samples of E. coli after 33 growth cycles of a minimum inhibitory challenge to E. coli by poly(amidoamine) dendrimers functionalized with mannose and with C₁₆-DABCO quaternary ammonium endgroups and compared to the metabolic profile of wild type E. coli.

Results

The wild type and mutated E. coli samples were separated into distinct sample sets by hierarchical clustering, principal component analysis (PCA) and sparse partial least squares discriminate analysis (sPLS-DA). Metabolite components of membrane fortification and energy related pathways had a significant p value and fold change between the wild type and mutated E. coli. Amino acids commonly associated with membrane fortification from cationic antimicrobials, such as lysine, were found to have a higher concentration in the mutated E. coli than in the wild type E. coli. N-acetylglucosamine, a major component of peptidoglycan synthesis, was found to have a 25-fold higher concentration in the mid log phase of the mutated E. coli than in the mid log phase of the wild type.

Conclusion

The metabolic profile suggests that E. coli change their peptidoglycan composition in order to garner protection from the highly positively charged and multivalent C₁₆-DABCO and mannose functionalized dendrimer.

中文翻译：

---

使用多价季铵官能化大分子对细菌耐药途径进行核磁共振代谢组学分析。

介绍

多价抗菌树枝状大分子是一种令人兴奋的新系统，正在开发以解决日益严重的耐药细菌问题。核磁共振 (NMR) 代谢组学是一种定量且可重复的方法，用于确定细菌对环境压力源的反应和可视化对生化途径的扰动。

目标

NMR 代谢组学用于阐明野生型和抗菌突变大肠杆菌（大肠杆菌）样品之间的代谢物差异。

方法

在用甘露糖和 C ₁₆ -DABCO 季铵端基官能化的聚(酰氨基胺)树枝状大分子对大肠杆菌进行 33 个最小抑制挑战的生长周期后，对大肠杆菌样品进行质子 ( ¹ H) NMR 亲水代谢物分析，并进行比较野生型大肠杆菌的代谢特征。

结果

通过层次聚类、主成分分析 (PCA) 和稀疏偏最小二乘判别分析 (sPLS-DA)将野生型和突变的大肠杆菌样品分成不同的样品组。膜强化和能量相关途径的代谢物成分在野生型和突变型大肠杆菌之间具有显着的 p 值和倍数变化。发现通常与阳离子抗微生物剂的膜强化相关的氨基酸（例如赖氨酸）在突变大肠杆菌中的浓度高于野生型大肠杆菌。ñ-乙酰氨基葡糖是肽聚糖合成的主要成分，被发现在突变大肠杆菌的对数中期比野生型对数中期的浓度高 25 倍。

结论

代谢特征表明，大肠杆菌改变了它们的肽聚糖组成，以获得对高正电荷和多价 C ₁₆ -DABCO 和甘露糖功能化树枝状聚合物的保护。