Cadmium (Cd) is a widespread contaminant in aquatic systems and has a variety of toxicological implications on freshwater microorganisms. In this study, the green algae Scenedesmus obliquus was exposed to increasing Cd concentrations that inhibited growth by 20% (12.6 μmol L⁻¹), 30% (39.8 μmol L⁻¹) and 40% (83.2 μmol L⁻¹) and the metabolite profiles of released and cellular biomolecules were explored using an untargeted direct infusion high resolution Fourier transform ion cyclotron resonance mass spectrometry approach. In Cd untreated cultures, intrinsic differences in composition existed between released biomolecules and freeze-dried cells. Based on putatively characterized compound groups, a greater proportion of Cys-GSH isomers and carboxyamides were present in exudates whereas sugar isomers and phosphonic acids comprised most cellular metabolites. In cultures exposed to 83.2 μmol L⁻¹ Cd, an overall shift in metabolomic response across both released biomolecules and cellular components resulting in an increase of lipid-based esters, and Cys-GSH isomers. These two important metabolites are used in antioxidant defense mechanisms and reactive oxygen species prevention during cellular stress. The diversity of metabolites also decreased as Cd concentrations increased when compared to untreated cultures, suggesting that overall metabolites specialize upon metal stress. We show systemic shifts from sugar and carboxylic isomers to specialized proteins and lipid isomers to help S. obliquus cope with stress. These findings highlight the potential use of this green algae as a potential biosorbent and sheds light into the metabolomics of Cd toxicology and insights into microbial metal adaptation.

镉是水生系统中的一种广泛污染物，对淡水微生物有多种毒理学影响。在这项研究中，绿藻斜生栅藻是暴露于增加镉浓度抑制生长20％（12.6微摩尔大号^-1），30％（39.8微摩尔大号^-1）和40％（83.2微摩尔大号^-1），并使用非靶向直接输注高分辨率傅里叶变换离子回旋共振质谱方法研究了释放的和细胞生物分子的代谢物谱。在未经镉处理的培养物中，释放的生物分子和冻干细胞之间存在固有的组成差异。基于推定特征的化合物基团，渗出物中存在较大比例的Cys-GSH异构体和羧酰胺，而糖异构体和膦酸则占大多数细胞代谢产物。在暴露于83.2μmolL ^-1的培养物中Cd，释放的生物分子和细胞组分之间的代谢组学响应发生整体变化，导致脂质基酯和Cys-GSH异构体的数量增加。这两种重要的代谢物用于细胞应激期间的抗氧化防御机制和活性氧的预防。与未经处理的培养物相比，随着Cd浓度的增加，代谢物的多样性也降低了，这表明整体代谢物专门针对金属胁迫。我们显示了从糖和羧酸的异构体到专门的蛋白质和脂质异构体的系统性转变，以帮助斜S应对压力。这些发现凸显了这种绿藻作为潜在的生物吸附剂的潜在用途，并为Cd毒理学的代谢组学和微生物金属适应性提供了见识。