Ahmad Fiaz, Manefield Michael
Key Laboratory for Space Bioscience & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, 710072, People's Republic of China.
School of Civil and Environmental Engineering, University of New South Wales (UNSW), Sydney, 2052, New South Wales, Australia.
Heliyon. 2024 Aug 15;10(16):e36366. doi: 10.1016/j.heliyon.2024.e36366. eCollection 2024 Aug 30.
The escalating contamination caused by lead ions (Pb⁺) and its harmful effects on all life forms has raised global concerns. Certain microalgae thrive in metal mining sites characterized by low pH and high concentrations of Pb⁺, which are usually prohibitive for many microorganisms. Little is known about the mechanisms underlying the adaptation of such microalgae to these hostile conditions. In this study, we elucidated the adaptive strategies of the green microalga strain AUMW, isolated from a lead mining site, and its application for the removal of Pb. Results revealed that strain AUMW can efficiently tolerate up to 200 ppm of Pb in an F/2 medium. Further experimental variables were optimized through response surface methodology (RSM), and 99.6 % removal of Pb⁺ was achieved. Novel adaptive responses of strain AUMW to high levels of Pb⁺ include: (i) activation of metal-protective response by modulation of quantum yield ( ) and non-photochemical quenching (NPQ) of photosystem II; (ii) extracellular silicification encapsulated cells of strain AUMW and altered cell morphology from oval to hexagonal; (iii) silicification prevented intracellular translocation of Pb; (iv) silicification boosted adsorption of Pb, thus enhanced its removal. This study offers new insights into the protective role of silicification in green microalgae and its potential for the removal of metals from metal-polluted sites, waste from energy storage battery industries, and spent batteries. It also provides a solid base to explore the genetic and metabolic pathways involved in the adaptation of strain AUMW to elevated levels of Pb.
铅离子（Pb⁺）造成的污染不断升级及其对所有生命形式的有害影响已引起全球关注。某些微藻在以低pH值和高浓度Pb⁺为特征的金属矿场中茁壮成长，而这些条件通常对许多微生物来说是不利的。对于此类微藻适应这些恶劣条件的潜在机制知之甚少。在本研究中，我们阐明了从铅矿场分离出的绿色微藻菌株AUMW的适应策略及其对铅的去除应用。结果表明，菌株AUMW在F/2培养基中能够有效耐受高达200 ppm的铅。通过响应面法（RSM）对进一步的实验变量进行了优化，实现了对Pb⁺的99.6%去除率。菌株AUMW对高浓度Pb⁺的新型适应性反应包括：（i）通过调节光系统II的量子产率（ ）和非光化学猝灭（NPQ）来激活金属保护反应；（ii）菌株AUMW细胞外硅化，细胞形态从椭圆形变为六边形；（iii）硅化防止了铅的细胞内转运；（iv）硅化促进了铅的吸附，从而提高了其去除率。本研究为硅化在绿色微藻中的保护作用及其从金属污染场地、储能电池行业的废物和废旧电池中去除金属的潜力提供了新的见解。它还为探索菌株AUMW适应高浓度铅所涉及的遗传和代谢途径提供了坚实的基础。
