Department of Life Sciences, Universidad de Alcalá, 28805 Alcalá de Henares, Madrid, Spain.
Marine Biotechnology Department, Stazione Zoologica Anton Dohrn, 80121, Naples, Italy.
Microb Ecol. 2021 Aug;82(2):334-343. doi: 10.1007/s00248-021-01685-z. Epub 2021 Jan 15.
Several studies on aeroterrestrial microalgae are unravelling their resistance mechanisms to different abiotic stressors, including hazardous metals, pointing to their future role as bioremediation microorganisms. In the present study, physiological and molecular alterations of four phycobionts of genus Trebouxia (T. TR1 and T. TR9) and Coccomyxa (C. subellipsoidea and C. simplex) exposed to Cd were studied. Cd accumulation and subcellular distribution, cell wall structure, production of biothiols (GSH and phytochelatins), reactive oxygen species (ROS) formation, expression of key antioxidant genes and ROS-related enzymes were evaluated to determine the physiological differences among the four microalgae, with the aim to identify the most suitable microorganism for further biotechnological applications. After 7 days of Cd exposure, Coccomyxa algae showed higher capacity of Cd intake than Trebouxia species, with C. subellipsoidea being the highest Cd accumulator at both intracellular and, especially, cell wall level. Cd induced ROS formation in the four microalgae, but to a greater extent in both Coccomyxa algae. Trebouxia TR9 showed the lowest Cd-dependent oxidative stress probably due to glutathione reductase induction. All microalgae synthetized phytochelatins in response to Cd but in a species-specific and a dose-dependent manner. Results from this study agree with the notion that each microalga has evolved a distinct strategy to detoxify hazardous metals like Cd and to cope with oxidative stress associated with them. Coccomyxa subellipsoidea and Trebouxia TR9 appear as the most interesting candidates for further applications.
几项关于气生微藻的研究揭示了它们对不同非生物胁迫因素（包括有害金属）的抗性机制，这表明它们未来可能作为生物修复微生物发挥作用。在本研究中，研究了四种属的蓝藻（Trebouxia 的 TR1 和 TR9 以及 Coccomyxa 的 C. subellipsoidea 和 C. simplex）暴露于 Cd 时的生理和分子变化。评估了 Cd 的积累和亚细胞分布、细胞壁结构、生物硫醇（GSH 和植物螯合肽）的产生、活性氧物种（ROS）的形成、关键抗氧化基因和 ROS 相关酶的表达，以确定四种微藻之间的生理差异，目的是确定最适合进一步生物技术应用的微生物。在 Cd 暴露 7 天后，Coccomyxa 藻类显示出比 Trebouxia 物种更高的 Cd 摄入能力，C. subellipsoidea 是细胞内和特别是细胞壁水平上最高的 Cd 积累者。Cd 诱导四种微藻中 ROS 的形成，但在两种 Coccomyxa 藻类中更为明显。Trebouxia TR9 显示出最低的 Cd 依赖性氧化应激，可能是由于谷胱甘肽还原酶的诱导。所有微藻都合成了植物螯合肽以应对 Cd，但具有物种特异性和剂量依赖性。本研究结果与以下观点一致，即每种微藻都进化出一种独特的策略来解毒有害金属如 Cd，并应对与之相关的氧化应激。Coccomyxa subellipsoidea 和 Trebouxia TR9 似乎是进一步应用的最有前途的候选者。
