Phytohormone-Mediated Responses of Microalgae to Metal Stress: From Molecular Regulation to Potential Applications in Ecological Remediation

Abstract

Heavy metal pollution caused by industrial wastewater has posed a severe threat to water ecological security and human health. Traditional treatment technologies are limited by high costs and the risk of secondary pollution. In contrast, microalgal bioremediation technology, which features high efficiency, environmental friendliness, and potential for resource recycling, has emerged as a cutting-edge research focus. This study systematically examines the toxic response mechanisms of microalgae under heavy metal stress, including lipid peroxidation-mediated membrane damage, obstruction of the photosynthetic electron transport chain, competitive inhibition of key enzyme activities, and reactive oxygen species (ROS)-triggered oxidative stress cascades. Furthermore, the tolerance mechanisms of microalgae are thoroughly analyzed, encompassing cell wall adsorption, activation of antioxidant defense systems, regulation of metal transporters, and coordination of phytohormone signaling networks. Phytohormones mitigate heavy metal stress by modulating the expression of cell division-related genes, influencing metal transporter synthesis, enhancing membrane stability, and activating antioxidant enzymes. This study also incorporates multi-omics analyses and discusses the potential of synthetic biology approaches to engineer phytohormone metabolic pathways, with the aim of developing smart, heavy metal-responsive microalgal strains. This provides a systematic framework from fundamental mechanism analysis to applied innovation, promoting the development of microalgal bioremediation technology toward greater precision and intelligence.

Keywords

microalgae / phytohormone / heavy metal stress / bioremediation / molecular regulation

References

[1] Alharbi, R.M.; Abdel-Raouf N.; Mohamed M.S.; et al. Phycomediation of cadmium contaminated aqueous solutions using Chlamydomonas sp.: Process optimization and adsorption characterization. Front. Bioeng. Biotechnol. 2025, 13, 1558757.

[2] Gupta, N.; Arunachalam, S. Assessment of human health risks posed by toxic heavy metals in Tilapia fish (Oreochromis mossambicus) from the Cauvery River, India. Front. Public Health 2024, 12, 1402421.

[3] Wei,Y.; Song, L.; Ma, Y.; et al. Sedimentary heavy metal interactions with phytoplankton and zooplankton across the Bohai Sea. J. Environ. Manag. 2025, 381, 125226.

[4] Iddrisu, L.; Danso F.; Cheong, K.-L.; et al. Polysaccharides as Protective Agents against Heavy Metal Toxicity. Foods 2024, 13, 853.

[5] Saravanan, P.; Saravanan V.; Rajeshkannan R.; et al. Comprehensive review on toxic heavy metals in the aquatic system: Sources, identification, treatment strategies, and health risk assessment. Environ. Res. 2024, 258, 119440.

[6] Jomova, K.; Alomar S.Y.; Nepovimova E.; et al. Heavy metals: Toxicity and human health effects. Arch. Toxicol. 2025, 99, 153-209.

[7] Fei, Y.; Hu, Y.H. Recent progress in removal of heavy metals from wastewater: A comprehensive review. Chemosphere 2023, 335, 139077.

[8] Mandal,R.R.; Bashir, Z.; Raj, D. Microbe-assisted phytoremediation for sustainable management of heavy metal in wastewater—A green approach to escalate the remediation of heavy metals. J. Environ. Manag. 2025, 375, 124199.

[9] Sopanrao, K.S.; Venugopal A.; Patel C.M.; et al. Phosphoric acid-modified bentonite-chitosan composite beads: A novel and cost-effective adsorbent for multi-metal wastewater treatment. Environ. Sci. Pollut. Res. 2024. https://doi.org/10.1007/s11356-024-35653-0.

[10] Anderson, A.; Anbarasu A.; Pasupuleti, R.R.; et al. Treatment of heavy metals containing wastewater using biodegradable adsorbents: A review of mechanism and future trends. Chemosphere 2022, 295, 133724.

[11] Ding,C.; Ding, Z.; Liu, Q.; et al. Advances in mechanism for the microbial transformation of heavy metals: Implications for bioremediation strategies. Chem. Commun. 2024, 60, 12315-12332.

[12] Chan, S.S.; Khoo K.S.; Abdullah R.; et al. Harnessing microalgae for metal nanoparticles biogenesis using heavy metal ions from wastewater as a metal precursor: A review. Sci. Total Environ. 2024, 957, 176989.

[13] Aneja, R.K.; Chaudhary G.; Ahluwalia S.S.; et al. Biosorption of Pb2+ and Zn2+ by Non-Living Biomass of Spirulina sp. Indian J. Microbiol. 2011, 50, 438-442.

[14] Guo, Y.; Liu, L.; Shi, X.; et al. Overexpression of the RAV Transcription Factor OsAAT 1 Confers Enhanced Arsenic Tolerance by Modulating Auxin Hemostasis in Rice. J. Agric. Food Chem. 2024, 72, 24576-24586.

[15] Gu,J.J.; Dou, X.X.; Zhou, J.L.; et al. Phytohormone-augmented microalgae: A dual-functional solution for pharmaceutical contaminants removal and resource recovery. J. Hazard. Mater. 2025, 496, 139379.

[16] Manikandan, A.; Suresh Babu P.; Shyamalagowri S.; et al. Emerging role of microalgae in heavy metal bioremediation. J. Basic Microbiol. 2022, 62, 330-347.

[17] Piotrowska-Niczyporuk, A.; Bajguz A.; Kotowska U.; et al. Auxins and Cytokinins Regulate Phytohormone Homeostasis and Thiol-Mediated Detoxification in the Green Alga Acutodesmus obliquus Exposed to Lead Stress. Sci. Rep. 2020, 10, 10193.

[18] Abdelfattah, A.; Ali S.S.; Ramadan H.; et al. Microalgae-based wastewater treatment: Mechanisms, challenges, recent advances, and future prospects. Environ. Sci. Ecotechnol. 2023, 13, 100205.

[19] Wang, C.; Qi, M.; Guo, J.; et al. The Active Phytohormone in Microalgae: The Characteristics, Efficient Detection, and Their Adversity Resistance Applications. Molecules 2021, 27, 46.

[20] Khavari, F.; Saidijam M.; Taheri M.; et al. Microalgae: Therapeutic potentials and applications. Mol. Biol. Rep. 2021, 48, 4757-4765.

[21] Tounosu, N.; Sesoko K.; Hori, K.; et al. Cis-regulatory elements and transcription factors related to auxin signaling in the streptophyte algae Klebsormidium nitens. Sci. Rep. 2023, 13, 9635.

[22] Monteiro, C.M.; Castro, P.M.; Malcata, F.X. Metal uptake by microalgae: Underlying mechanisms and practical applications. Biotechnol. Prog. 2012, 28, 299-311.

[23] Duan, L.; Jiang H.; Cai, B.; et al. Selective ·OH generation in Fenton-like reaction by dual sulfur coordination of iron organic frameworks. Water Res. 2025, 282, 123653.

[24] Wang, S.; Yang, S.; Wang, J. The combined effects of copper and zinc on Arabidopsis involve differential regulation of chlorophyll synthesis and photosystem function. Plant Physiol. Biochem. PPB 2024, 216, 109160.

[25] Fettweis, A.; Bergen B.; Hansul S.; et al. Correlated Ni, Cu, and Zn Sensitivities of 8 Freshwater Algal Species and Consequences for Low-Level Metal Mixture Effects. Environ. Toxicol. Chem. 2021, 40, 2013-2023.

[26] Hamed, S.M.; Zinta G.; Klöck G.; et al. Zinc-induced differential oxidative stress and antioxidant responses in Chlorella sorokiniana and Scenedesmus acuminatus. Ecotoxicol. Environ. Saf. 2017, 140, 256-263.

[27] Dos Reis, L.L.; Alho, L.O.G.; de Abreu, C.B.; et al. Using multiple endpoints to assess the toxicity of cadmium and cobalt for chlorophycean Raphidocelis subcapitata. Ecotoxicol. Environ. Saf. 2021, 208, 111628.

[28] Leong,Y.K.; Chang, J.S. Bioremediation of heavy metals using microalgae: Recent advances and mechanisms. Bioresour. Technol. 2020, 303, 122886.

[29] Poyton, M.F.; Pullanchery S.; Sun, S.; et al. Zn(2+) Binds to Phosphatidylserine and Induces Membrane Blebbing. J. Am. Chem. Soc. 2020, 142, 18679-18686.

[30] Liu, H.; Chen S.; Zhang H.; et al. Effects of copper sulfate algaecide on the cell growth, physiological characteristics, the metabolic activity of Microcystis aeruginosa and raw water application. J. Hazard. Mater. 2023, 445, 130604.

[31] Shomali, A.; Das S.; Sarraf M.; et al. Modulation of plant photosynthetic processes during metal and metalloid stress, and strategies for manipulating photosynthesis-related traits. Plant Physiol. Biochem. PPB 2024, 206, 108211.

[32] Da,X.; Guo, J.; Yan, P.; et al. Characterizing membrane anchoring of leaf-form ferredoxin-NADP(+) oxidoreductase in rice. Plant Cell Environ. 2023, 46, 1195-1206.

[33] Liu,L.; Li, S.; Guo, J.; et al. Low temperature tolerance is depressed in wild-type and abscisic acid-deficient mutant barley grown in Cd-contaminated soil. J. Hazard. Mater. 2022, 430, 128489.

[34] Leon-Vaz, A.; Romero L.C.; Gotor C.; et al. Effect of cadmium in the microalga Chlorella sorokiniana: A proteomic study. Ecotoxicol. Environ. Saf. 2021, 207, 111301.

[35] Chen, F.; Pan, X.; Luo, Z.; et al. Enhancing rice (Oryza sativa L.) resilience to cadmium stress through nanoparticle and rhizobacterial strategies: A sustainable approach to heavy metal remediation. Environ. Pollut. 2025, 383, 126847.

[36] Sychta, K.; Slomka, A.; Kuta, E. Insights into Plant Programmed Cell Death Induced by Heavy Metals-Discovering a Terra Incognita. Cells 2021, 10, 65.

[37] El-Samad, L.M.; Arafat E.A.; Nour, O.M.; et al. Biomonitoring of Heavy Metal Toxicity in Freshwater Canals in Egypt Using Creeping Water Bugs (Ilyocoris cimicoides): Oxidative Stress, Histopathological, and Ultrastructural Investigations. Antioxidants 2024, 13, 1309.

[38] Nowicka, B. Heavy metal-induced stress in eukaryotic algae-mechanisms of heavy metal toxicity and tolerance with particular emphasis on oxidative stress in exposed cells and the role of antioxidant response. Environ. Sci. Pollut. Res. Int. 2022, 29, 16860-16911.

[39] Tang, D.; Li X.; Zhang L.; et al. Reactive oxygen species-mediated signal transduction and utilization strategies in microalgae. Bioresour. Technol. 2025, 418, 132004.

[40] Nguyen, N.H.; Nguyen Q.T.; Dang, D.H.; et al. Phytohormones enhance heavy metal responses in Euglena gracilis: Evidence from uptake of Ni, Pb and Cd and linkages to hormonomic and metabolomic dynamics. Environ. Pollut. 2023, 320, 121094.

[41] Du,F.; Wang, Y.; Wang, J.; et al. The basic helix-loop-helix transcription factor gene, OsbHLH38, plays a key role in controlling rice salt tolerance. J. Integr. Plant Biol. 2023, 65, 1859-1873.

[42] Narayanan, M.; Ma, Y. Mitigation of heavy metal stress in the soil through optimized interaction between plants and microbes. J. Environ. Manag. 2023, 345, 118732.

[43] Li, C.; Zheng, C.; Fu, H.; et al. Contrasting detoxification mechanisms of Chlamydomonas reinhardtii under Cd and Pb stress. Chemosphere 2021, 274, 129771.

[44] Zhang,Y.; Zhan, J.; Ma, C.; et al. Root-associated bacterial microbiome shaped by root selective effects benefits phytostabilization by Athyrium wardii ( Hook.). Ecotoxicol. Environ. Saf. 2024, 269, 115739.

[45] Danouche, M.; El Ghatchouli, N.; Arroussi, H. Overview of the management of heavy metals toxicity by microalgae. J. Appl. Phycol. 2022, 34, 475-488.

[46] Li,N.; Wang, P.; Wang, S.; et al. Electrostatic charges on microalgae surface: Mechanism and applications. J. Environ. Chem. Eng. 2022, 10, 107516.

[47] Sultana, N.; Hossain S.M.Z.; Mohammed M.E.; et al. Experimental study and parameters optimization of microalgae based heavy metals removal process using a hybrid response surface methodology-crow search algorithm. Sci. Rep. 2020, 10, 15068.

[48] Tripathi, S.; Poluri, K.M. Heavy metal detoxification mechanisms by microalgae: Insights from transcriptomics analysis. Environ. Pollut. 2021, 285, 117443.

[49] Spain, O.; Plohn, M.; Funk, C. The cell wall of green microalgae and its role in heavy metal removal. Physiol. Plant. 2021, 173, 526-535.

[50] Zhang,L.; Li, N.; Xiao, X.; et al. Physiological and transcriptomic responses of the microalga Isochrysis galbana during exposure to Hg(II) stress. World J. Microbiol. Biotechnol. 2025, 41, 164.

[51] Balzano, S.; Sardo A.; Blasio M.; et al. Microalgal Metallothioneins and Phytochelatins and Their Potential Use in Bioremediation. Front. Microbiol. 2020, 11, 517.

[52] CHENG Z, WANG C, TANG F, et al. The cell wall functions in plant heavy metal response[J]. Ecotoxicology and environmental safety, 2025, 299: 118326.

[53] Xia, L.; Li, H.; Song, S. Cell surface characterization of some oleaginous green algae. J. Appl. Phycol. 2016, 28, 2323-2332.

[54] Cavalletti, E.; Romano G.; Palma Esposito, F.; et al. Copper Effect on Microalgae: Toxicity and Bioremediation Strategies. Toxics 2022, 10, 527.

[55] Xiao,X.; Li, W.; Jin, M.; et al. Responses and tolerance mechanisms of microalgae to heavy metal stress: A review. Mar. Environ. Res. 2023, 183, 105805.

[56] Rezayian, M.; Niknam, V.; Ebrahimzadeh, H. Oxidative damage and antioxidative system in algae. Toxicol. Rep. 2019, 6, 1309-1313.

[57] Liu, A.; Zhang L.; Zhou, A.; et al. Metabolomic and physiological changes of acid-tolerant Graesiella sp. MA 1 during long-term acid stress. Environ. Sci. Pollut. Res. Int. 2023, 30, 97209-97218.

[58] Sun,X.M.; Ren, L.J.; Zhao, Q.Y.; et al. Enhancement of lipid accumulation in microalgae by metabolic engineering. Biochim. Biophys. Acta Mol. Cell Biol. Lipids 2019, 1864, 552-566.

[59] Dahuja, A.; Kumar R.R.; Sakhare A.; et al. Role of ATP-binding cassette transporters in maintaining plant homeostasis under abiotic and biotic stresses. Physiol. Plant. 2021, 171, 785-801.

[60] Danouche, M.; El Ghachtouli, N.; El Arroussi, H. Phycoremediation mechanisms of heavy metals using living green microalgae: Physicochemical and molecular approaches for enhancing selectivity and removal capacity. Heliyon 2021, 7, e07609.

[61] Lu, Y.; Xu, J. Phytohormones in microalgae: A new opportunity for microalgal biotechnology? Trends Plant Sci. 2015, 20, 273-282.

[62] Stirk, W.A.; Ördög V.; Novák O.; et al. Auxin and cytokinin relationships in 24 microalgal strains1. J. Phycol. 2013, 49, 459-467.

[63] Romanenko, K.; Kosakovskaya, I.; Romanenko, P. Phytohormones of Microalgae: Biological Role and Involvement in the Regulation of Physiological Processes. Int. J. Algae 2016, 18, 179-201.

[64] Shah, S.; Li X.; Jiang Z.; et al. Exploration of the phytohormone regulation of energy storage compound accumulation in microalgae. Food Energy Secur. 2022, 11, e418.

[65] Zhou, J.L.; Vadiveloo A.; Chen, D.Z.; et al. Regulation effects of indoleacetic acid on lipid production and nutrient removal of Chlorella pyrenoidosa in seawater-containing wastewater. Water Res. 2024, 248, 120864.

[66] Stirk, W.A.; Van Staden, J. Potential of phytohormones as a strategy to improve microalgae productivity for biotechnological applications. Biotechnol. Adv. 2020, 44, 107612.

[67] Jusoh,M.; Loh, S.H.; Aziz, A.; et al. Gibberellin Promotes Cell Growth and Induces Changes in Fatty Acid Biosynthesis and Upregulates Fatty Acid Biosynthetic Genes in Chlorella vulgaris UMT-M1. Appl. Biochem. Biotechnol. 2019, 188, 450-459.

[68] Yu,Z.; Song, M.; Pei, H.; et al. The effects of combined agricultural phytohormones on the growth, carbon partitioning and cell morphology of two screened algae. Bioresour. Technol. 2017, 239, 87-96.

[69] Sun,X.M.; Ren, L.J.; Zhao, Q.Y.; et al. Application of chemicals for enhancing lipid production in microalgae-a short review. Bioresour. Technol. 2019, 293, 122135.

[70] Piotrowska-Niczyporuk, A.; Bajguz A.; Zambrzycka-Szelewa E.; et al. Exogenously applied auxins and cytokinins ameliorate lead toxicity by inducing antioxidant defence system in green alga Acutodesmus obliquus. Plant Physiol. Biochem. PPB 2018, 132, 535-546.

[71] Zhao,Y.; Wang, H.P.; Han, B.; et al. Coupling of abiotic stresses and phytohormones for the production of lipids and high-value by-products by microalgae: A review. Bioresour. Technol. 2019, 274, 549-556.

[72] Zamora, O.; Schulze S.; Azoulay-Shemer T.; et al. Jasmonic acid and salicylic acid play minor roles in stomatal regulation by CO2, abscisic acid, darkness, vapor pressure deficit and ozone. Plant J. Cell Mol. Biol. 2021, 108, 134-150.

[73] Owusu, V.; Mira M.; Soliman, A.; et al. Suppression of the maize phytoglobin ZmPgb1.1 promotes plant tolerance against Clavibacter nebraskensis. Planta 2019, 250, 1803-1818.

[74] Wang,W.; Sun, Y.; Li, G.; et al. Brassinosteroids promote parenchyma cell and secondary xylem development in sugar beet ( Beta vulgaris L.) root. Plant Direct 2021, 5, e340.

[75] Dadras, A.; Duminil P.; de Vries S.; et al. Algal origins of core land plant stress response subnetworks. Plant J. Cell Mol. Biol. 2025, 122, e70291.

[76] Komatsu, K.; Takezawa, D.; Sakata, Y. Decoding ABA and osmostress signalling in plants from an evolutionary point of view. Plant Cell Environ. 2020, 43, 2894-2911.

[77] Jusoh, M.; Loh S.H.; Chuah T.S.; et al. Elucidating the role of jasmonic acid in oil accumulation, fatty acid composition and gene expression in Chlorella vulgaris (Trebouxiophyceae) during early stationary growth phase. Algal Res. 2015, 9, 14-20.

[78] Zhang, N.X.; Messelink G.J.; Alba, J.M.; et al. Phytophagy of omnivorous predator Macrolophus pygmaeus affects performance of herbivores through induced plant defences. Oecologia 2018, 186, 101-113.

[79] Carrillo-Carrasco, V.P.; van Galen M.; Bronkhorst J.; et al. Auxin and tryptophan trigger common responses in the streptophyte alga Penium margaritaceum. Curr. Biol. 2025, 35, 2078-2087.e4.

[80] Zhao,D.; Wang, H.; Chen, S.; et al. Phytomelatonin: An Emerging Regulator of Plant Biotic Stress Resistance. Trends Plant Sci. 2021, 26, 70-82.

[81] Khasin, M.; Cahoon R.E.; Alvarez S.; et al. Synthesis, secretion, and perception of abscisic acid regulates stress responses in Chlorella sorokiniana. bioRxiv 2017, 180547. https://doi.org/10.1101/180547.

[82] Hernández-García, J.; Briones-Moreno A.; Dumas R.; et al. Origin of Gibberellin-Dependent Transcriptional Regulation by Molecular Exploitation of a Transactivation Domain in DELLA Proteins. Mol. Biol. Evol. 2019, 36, 908-918.

[83] Zamani-Ahmadmahmoodi, R.; Malekabadi M.B.; Rahimi R.; et al. Aquatic pollution caused by mercury, lead, and cadmium affects cell growth and pigment content of marine microalga, Nannochloropsis oculata. Environ. Monit. Assess. 2020, 192, 330.

[84] Zhao, Y.; Ngo, H.H.; Yu, X. Phytohormone-like small biomolecules for microalgal biotechnology. Trends Biotechnol. 2022, 40, 1025-1028.

[85] Papry, R.I.; Fujisawa S.; Yinghan Z.; et al. Integrated effects of important environmental factors on arsenic biotransformation and photosynthetic efficiency by marine microalgae. Ecotoxicol. Environ. Saf. 2020, 201, 110797.

[86] da Silva Ferreira, V.; Sant’anna, C. Impact of culture conditions on the chlorophyll content of microalgae for biotechnological applications. World J. Microbiol. Biotechnol. 2017, 33, 20.

[87] Yang, J.; Li, W.; Xing, C.; et al. Ca²⁺ participates in the regulation of microalgae triacylglycerol metabolism under heat stress. Environ. Res. 2022, 208, 112696.

[88] Wang,W.; Xue, Y.; Li, B.; et al. Effect of peroxisome proliferation and salt stress on enhancing the potential of microalgae as biodiesel feedstock. Renew. Sustain. Energy Rev. 2025, 212, 115398.

[89] Gonçalves,S.C.; Cui, Z.; Kumar, K.S. Editorial: Biotechnological solutions to assess, monitor and remediate metal pollution in the marine environment. Front. Mar. Sci. 2024, 11, 1345500.

[90] Lobus, N.V.; Kulikovskiy, M.S. The Co-Evolution Aspects of the Biogeochemical Role of Phytoplankton in Aquatic Ecosystems: A Review. Biology 2023, 12, 92.

[91] Mok,M.C.; Martin, R.C.; Mok, D.W.S. Cytokinins: Biosynthesis metabolism and perception. Vitr. Cell. Dev. Biol. Plant 2000, 36, 102-107.

[92] Kumar, S.; Shah S.H.; Vimala Y.; et al. Abscisic acid: Metabolism, transport, crosstalk with other plant growth regulators, and its role in heavy metal stress mitigation. Front. Plant Sci. 2022, 13, 972856.

[93] Basu,S.; Rabara, R. Abscisic acid—An enigma in the abiotic stress tolerance of crop plants. Plant Gene 2017, 11, 90-98.

[94] Nguyen,H.N.; Kisiala, A.B.; Emery, R.J.N. The roles of phytohormones in metal stress regulation in microalgae. J. Appl. Phycol. 2020, 32, 3817-3829.

[95] Ghosh, A.; Sah D.; Chakraborty M.; et al. Mechanism and application of bacterial exopolysaccharides: An advanced approach for sustainable heavy metal abolition from soil. Carbohydr. Res. 2024, 544, 109247.

[96] Verma,N.; Prasad, S.M. Regulation of redox homeostasis in cadmium stressed rice field cyanobacteria by exogenous hydrogen peroxide and nitric oxide. Sci. Rep. 2021, 11, 2893.

[97] Yoshida, T.; Fujita Y.; Sayama H.; et al. AREB1, AREB2, and ABF 3 are master transcription factors that cooperatively regulate ABRE-dependent ABA signaling involved in drought stress tolerance and require ABA for full activation. Plant J. Cell Mol. Biol. 2010, 61, 672-685.

[98] Ibuot,A.; Dean, A.; Pittman, J. Characterisation of Metal Transport Proteins for providing metal stress tolerance in green microalgae. New Biotechnol. 2014, 31, S141.

[99] Wang,J.; Song, L.; Gong, X.; et al. Functions of Jasmonic Acid in Plant Regulation and Response to Abiotic Stress. Int. J. Mol. Sci. 2020, 21, 1446.

[100] Shinshi, H. Ethylene-regulated transcription and crosstalk with jasmonic acid. Plant Sci. 2008, 175, 18-23.

[101] Li, G.; Xu W.; Kronzucker H.J.; et al. Ethylene is critical to the maintenance of primary root growth and Fe homeostasis under Fe stress in Arabidopsis. J. Exp. Bot. 2015, 66, 2041-2054.

[102] Zhang, M.; Zhao, X.; Ren, X. Research Progress on the Mechanisms of Algal-Microorganism Symbiosis in Enhancing Large-Scale Lipid Production. J. Agric. Food Chem. 2025, 73, 6345-6360.

[103] Ran,Y.; Sun, D.; Liu, X.; et al. Chlorella pyrenoidosa as a potential bioremediator: Its tolerance and molecular responses to cadmium and lead. Sci. Total Environ. 2024, 912, 168712.

[104] Peng, H.; De-Bashan, L.E.; Higgins, B.T. Azospirillum brasilense reduces oxidative stress in the green microalgae Chlorella sorokiniana under different stressors. J. Biotechnol. 2021, 325, 179-185.

[105] Piotrowska-Niczyporuk, A.; Bajguz A.; Zambrzycka E.; et al. Phytohormones as regulators of heavy metal biosorption and toxicity in green alga Chlorella vulgaris (Chlorophyceae). Plant Physiol. Biochem. PPB 2012, 52, 52-65.

[106] Piotrowska-Niczyporuk, A.; Bonda-Ostaszewska, E.; Bajguz, A. Mitigating Effect of Trans-Zeatin on Cadmium Toxicity in Desmodesmus armatus. Cells 2024, 13, 686.

[107] Ibuot, A.; Dean A.P.; Mcintosh O.A.; et al. Metal bioremediation by CrMTP 4 over-expressing Chlamydomonas reinhardtii in comparison to natural wastewater-tolerant microalgae strains. Algal Res. 2017, 24, 89-96.

[108] Lin, Y.; Dai, Y.; Xu, W.; et al. The Growth, Lipid Accumulation and Fatty Acid Profile Analysis by Abscisic Acid and Indol-3-Acetic Acid Induced in Chlorella sp. FACHB-8. Int. J. Mol. Sci. 2022, 23, 4064.

[109] Yuan, H.; Zhang X.; Jiang Z.; et al. Analyzing the effect of pH on microalgae adhesion by identifying the dominant interaction between cell and surface. Colloids Surf. B Biointerfaces 2019, 177, 479-486.

[110] Abinandan, S.; Venkateswarlu, K.; Megharaj, M. Phenotypic changes in microalgae at acidic pH mediate their tolerance to higher concentrations of transition metals. Curr. Res. Microb. Sci. 2021, 2, 100081.

[111] Chen,F.; Chen, Y.; Pan, K.; et al. Species-specific deformation of microalgae in the presence of microplastics. Environ. Chem. Lett. 2024, 22, 953-959.

[112] Ismaiel, M.M.S.; Piercey-Normore, M.D.; Rampitsch, C. Biochemical and proteomic response of the freshwater green alga Pseudochlorella pringsheimii to iron and salinity stressors. BMC Plant Biol. 2024, 24, 42.