Assessing indicators of arsenic toxicity using variable fluorescence in a commercially valuable microalgae: Physiological and toxicological aspects

• Published in: Journal of hazardous materials Vol. 452; p. 131215
• Main Authors: Das, Shagnika, Lizon, Fabrice, Gevaert, François, Bialais, Capucine, Duong, Gwendoline, Ouddane, Baghdad, Souissi, Sami
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.06.2023; Elsevier
• Subjects: Arsenic - toxicity; Arsenic bioaccumulation; Biomass; de-epoxidation ratio (DR); Diacronema lutheri; Ecosystem; Environmental Sciences; Fluorescence; Fluorometry; Microalgae; Optical absorption cross section; Photosynthesis; Pigment concentrations; Arsenic bioaccumulation; Diacronema lutheri; Pigment concentrations; Optical absorption cross section; de-epoxidation ratio (DR)
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.131215

Indicators signaling Arsenic (As) stress through physiology of microalgae using non-destructive methods like variable fluorescence are rare but requisite. This study reports stress markers indicating arsenic (As) toxicity (in two concentrations 11.25 µg/L and 22.5 µg/L compared to a control) exposed to a microalga (Diacronema lutheri), using fast repetition rate fluorometry (FRRf). Growth and physiological parameters such as cell density, chl a and the maximum quantum yield Fv/Fm showed coherence and impeded after the exponential phase (day 9 - day 12) in As treatments compared to the control (p < 0.05). On contrary photo-physiological constants were elevated showing higher optical (aLHII) and functional [Sigma (σPSII)] absorption cross-section for the As treatments (p < 0.05) further implying the lack of biomass production yet an increase in light absorption. In addition, As exposure increased the energy dissipation by heat (NPQ-NSV) showing a strong relationship with the de-epoxidation ratio (DR) involving photoprotective pigments. Total As bioaccumulation by D. lutheri showed a strong affinity with Fe adsorption throughout the algal growth curve. This study suggests some prompt photo-physiological proxies signaling As contamination and endorsing its usefulness in risk assessments, given the high toxicity and ubiquitous presence of As in the ecosystem. [Display omitted] •Arsenic (As) enhanced photoprotective processes and restricted biomass production.•Optical and functional absorption cross-section are useful indicators of As toxicity.•Non-photochemical quenching (NPQ-NSV) positively correlated to de-epoxidation ratio.•Significant affinity between Fe and As bioaccumulation by D. lutheri was observed.•Variable fluorescence endorsed an easy and compliant method to show As toxicity.