Effects of copper on photosynthetic and physiological parameters of a freshwater microalga (Chlorophyceae)

Autor(es)

Rocha, Giseli S. ^[1] ; Parrish, Christopher C. ^[2] ; Espindola, Evaldo L. G. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sao Carlos Sch Engn, NEEA CRHEA, Ave Trabalhador Saocarlense 400, BR-13566590 Sao Carlos, SP - Brazil

^[2] Mem Univ Newfoundland, Dept Ocean Sci, St John, NF A1C 5S7 - Canada

• Tipo de documento: Artigo Científico
• Fonte: ALGAL RESEARCH-BIOMASS BIOFUELS AND BIOPRODUCTS; v. 54, APR 2021.
• Citações Web of Science: 0

Resumo

Copper is known for its essentiality for optimal metabolism, and damage caused in algae under high exposure is also well documented; however, some mechanisms of its toxicity are still not totally understood. In the present study, we exposed the freshwater microalga Selenastrum gracile to sublethal copper concentrations and evaluated responses in algal growth, chlorophyll production, photosynthetic performance, and lipid class and fatty acid production. Excess metal impaired algal growth, but did not affect the production of chlorophyll per cell, which is consistent with the reported substitution of Mg2+ by Cu2+ in the chlorophyll molecule. With regards to photosynthesis, there was a decrease in the maximum quantum yield (similar to 20%) and the operational (effective) quantum yield was remarkably lower (similar to 60%) with excess of metal. The photochemical and non-photochemical quenchings were also affected with the presence of copper; however, there was no linear response according to the amount of metal, which suggests inactivation of reaction centers and damage to the photoprotection mechanisms. The amount of lipids and fatty acids increased with the increase of the metal, and the results indicate important roles of the proportions of structural lipids (sterol and phospholipids) and mono- and polyunsaturated fatty acids to maintain the photosynthetic structure; however, this was not enough to avoid damage of copper in the photoprotective mechanisms. As an outcome, the algae could not cope with excess of light under high amounts of metal, affecting the photochemical reactions and consequently photosynthetic activity. (AU)

• Processo FAPESP: 15/25436-1 - Influência de cobre e cádmio em alga e seus efeitos ecotoxicológicos em zooplâncton de água doce
• Beneficiário: Giseli Swerts Rocha
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado