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Comparative toxicity of physiological and biochemical parameters in Euglena gracilis to short-term exposure to potassium sorbate

Engel, Fernanda, Pinto, Luciano Henrique, Del Ciampo, Lineu Fernando, Lorenzi, Luciano, Heyder, Carmen Diamantina Teixeira, Häder, Donat Peter, Erzinger, Gilmar Sidnei
Ecotoxicology 2015 v.24 no.1 pp. 153-162
Euglena gracilis, acute toxicity, antioxidants, bacteria, bioassays, electron transfer, fish, human health, irradiation, photosynthesis, potassium sorbate, rats, sorbic acid
Potassium sorbate is the potassium salt of sorbic acid, is a widespread and efficient antioxidant that has multiple functions in plants, traditionally associated with the reactions of photosynthesis; however, it has moderate toxicity to various species including rat, fish, bacteria and human health. The effects of potassium sorbate on the movement and photosynthetic parameters of Euglena gracilis were studied during short-term exposure. Potassium sorbate showed acute toxicity to the green flagellate E. gracilis affecting different physiological parameters used as endpoints in an automatic bioassay such as motility, precision of gravitational orientation (r-value), upward movement and alignment, with mean EC₅₀values of 2867.2 mg L⁻¹. The concentrations above 625 mg L⁻¹of potassium sorbate induce an inhibition of the photosynthetic efficiency and electron transport rate and, in concentrations more than 2500.0 mg L⁻¹, the Euglena cells undergo a complete inhibition of photosynthesis even at low light irradiation.