Toxicity of organic (benzophenone-3) and inorganic (titanium dioxide and zinc oxide nanoparticles) ultraviolet filters on growth and metabolic activity of fungi cultured from the marine shallow-water hydrothermal vents of Kue

Abstract

The increased awareness of the damaging effects of ultraviolet radiation from the sun has promoted the use of sunscreen products. The active ingredients of sunscreen lotion, i.e., benzophenone-3 (BP-3), titanium dioxide (TiO2) nanoparticles (NPs), and zinc oxide (ZnO) NPs, can pollute the marine environment through runoff or human activities such as swimming. Early studies have revealed the toxic effects of these sunscreen active ingredients on aquatic animals, however, their effects on the marine decomposer community are less known, especially on fungi. This study investigated the effect of BP-3, TiO2 NPs, and ZnO NPs on growth and metabolic activity of selected fungi isolated from the marine shallow-water hydrothermal vent ecosystem at Kueishan Island, Taiwan. Growth inhibition was observed for the majority of the tested fungi (especially on Aspergillus spp.) by increased concentrations of ZnO NPs (0-100 mg/L). In contrast, TiO2 NPs and BP-3 exerted little effect on fungal growth. The differences in toxicity between ZnO NPs and TiO2 NPs might be attributed to variations in their solubility, size, and shape. Surprisingly, BP-3 exhibited the least toxicity on fungal growth, despite its known effects on other marine organisms at very low concentrations. The toxicity of ZnO NPs (12.5 mg/L) on the metabolic activity of the growth-inhibited fungi, using Biolog FF MicroPlate, was also examined, i.e., Aspergillus tubingensis NTOU5277, A. terreus NTOU5276, and A. terreus NTOU4989. A significant reduction in average well colour development (AWCD) was observed in the presence of ZnO NPs, suggesting an overall reduction in metabolic activity. Interestingly, the average well turbidity development (AWTD) of A. tubingensis NTOU5277 in the presence of ZnO NPs was higher than that of the control group without ZnO NPs, representing a higher average mycelial production. In terms of carbon utilization, D-galactose, gamma-hydroxy-butyric acid, and L-proline were not utilized by A. tubingensis NTOU5277 in the presence of ZnO NPs, with the latter two compounds related to the tricarboxylic acid (TCA) cycle. Aspergillus terreus isolates NTOU5276 and NTOU4989 showed a reduction in the utilization of L-phenylalanine and beta-hydroxy-butyric acid in the presence of ZnO NPs, respectively. These results suggest the potential toxic effects of ZnO NPs on energy production and metabolism in fungi and highlight the prospect of using Biolog FF MicroPlate for assessing metabolic effects of other anthropogenic pollutants on fungi.