The comprehensive effects of aluminum oxide nanoparticles on the physiology of freshwater microalga Scenedesmus obliquus and it's phycoremediation performance for the removal of sulfacetamide

Nanoparticles are inevitable byproducts of modern industry. However, the environmental impacts arising from industrial applications of nanoparticles are largely under-reported. This study evaluated the ecotoxicological effects of aluminum oxide nanoparticles (Al2O3NP) and its influence on sulfacetamide (SA) biodegradation by freshwater microalga, Scenedesmus obliquus. Although Al2O3NP showed limited toxicity effect on S. obliquus, observed the toxicity attenuation aspect of Al2O3NP in a mixture of sulfacetamide on microalgae. The addition 100 mg L(-1 )of Al2O3NP and 1 mg L(-1 )of SA reduced total chlorophyll by 23.3% and carotenoids by 21.6% microalgal compared to control. The gene expression study demonstrated that ATPF0C, Lhcb1, HydA, and psbA genes responsible for ATP synthesis and the photosynthetic system were significantly downregulated, while Tas gene, which plays a major role in biodegradation of organic xenobiotic chemicals, was significantly upre-gulated at 1 and 100 mg L(-1 )of Al2O3NP. The S. obliquus removed 16.8% of SA at 15 mg L-1 in 14 days. However, the removal was slightly enhanced (18.8%) at same concentration of SA in the presence of 50 mg L-1 Al2O3NP. This result proves the stability of sulfacetamide biodegradation capacity of S. obliquus in the presence of Al2O3NP co-contamination. The metabolic analysis showed that SA was degraded into simpler byproducts such as facarbamide, sulfaguanidine, sulfanilamide, 4-(methyl sulfonyl)aniline, and N-hydroxy-benzenamine which have lower ecotoxicity than SA, demonstrating that the ecotoxicity of sulfacetamide has significantly decreased after the microalgal degradation, suggesting the environmental feasibility of microalgae-mediated wastewater tech-nology. This study provides a deeper understanding of the impact of nanoparticles such as Al2O3NP on aquatic ecosystems.

Automated summary

This study evaluated the ecological toxicity of aluminum oxide nanoparticles (Al2O3NP) on freshwater microalgae and its influence on the biodegradation of sulfacetamide. The results showed that Al2O3NP had limited toxicity on the microalgae, but its presence attenuated the toxicity of sulfacetamide. The microalgae still exhibited a stable biodegradation capacity for sulfacetamide even in the presence of Al2O3NP.