RESUMO
Bisphenols (BPs) are recognized as emerging contaminants because of their estrogenic properties and frequent occurrence in environmental matrices. Here, we evaluated the toxic effects of five common BPs on freshwater microalga Chlamydomonas mexicana and removal of the BPs by the alga. Bisphenols -AF (BPAF), -B (BPB), and -Z (BPZ) (96 h, EC50 1.78-12.09 mg·L-1) exhibited higher toxicity to C. mexicana compared to bisphenol -S (BPS) and -F (BPF) (96 h, EC50 30.53-85.48 mg·L-1). In contrast, the mixture of BPs exhibited acute toxicity (96 h, EC50 8.07 mg·L-1). After 14 days, C. mexicana had effectively removed 61%, 99%, 55%, 87%, and 89% of BPS, BPF, BPAF, BPB, and BPZ, respectively, at 1 mg L-1. The biotransformed products of all five BPs were analyzed using UHPLC QTOF, and their toxicity was predicted. All biotransformed products were observed to be less toxic than the parent compounds. The fatty acid composition of C. mexicana after exposure to the BP mixture was predominantly palmitic acid (34.14%), followed by oleic acid (18.9%), and γ-linolenic acid (10.79%). The results provide crucial information on the ecotoxicity of these five BPs and their removal by C. mexicana; the resulting biomass is a potential feedstock for producing biodiesel.
Assuntos
Compostos Benzidrílicos , Chlamydomonas , Fenóis , Compostos Benzidrílicos/toxicidade , Biotransformação , Microalgas , Fenóis/toxicidade , Chlamydomonas/metabolismo , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidadeRESUMO
The effect of insecticides (acephate and imidacloprid) on a freshwater microalga Chlamydomonas mexicana was investigated with respect to photosynthetic pigments, carbohydrate and protein contents, fatty acids composition and induction of stress indicators including proline, superoxide dismutase (SOD) and catalase (CAT). C. mexicana was cultivated with 1, 5, 10, 15, 20 and 25 mg L(-1) of acephate and imidacloprid. The microalga growth increased with increasing concentrations of both insecticides up to 15 mg L(-1), beyond which the growth declined compared to control condition (without insecticides). C. mexicana cultivated with 15 mg L(-1) of both insecticides for 12 days was used for further analysis. The accumulation of photosynthetic pigments (chlorophyll and carotenoids), carbohydrates and protein was decreased in the presence of both insecticides. Acephate and imidacloprid induced the activities of superoxide dismutase (SOD) and catalase (CAT) and increased the concentration of proline in the microalga, which play a defensive role against various environmental stresses. Fatty acid analysis revealed that the fraction of polyunsaturated fatty acids decreased on exposure to both insecticides. C. mexicana also promoted 25 and 21% removal of acephate and imidacloprid, respectively. The biochemical changes in C. mexicana on exposure to acephate and imidacloprid indicate that the microalga undergoes an adaptive change in response to the insecticide-induced oxidative stress.