Dynamics of marine microorganisms harbouring catalases exposed to sunscreens and UV filters

Abstract

[eng] Coastal tourism growth combined with increasing awareness of UV radiation associated health risks caused a significant rise in the use of sunscreens in recent decades. The UV filters and other ingredients contained in solar sunscreens have been identified as emerging pollutants potentially harming marine organisms. However, studies on the impact of these compounds on marine microorganisms are limited, particularly in natural communities, despite their key role in global biogeochemical cycles and the trophic food web. To assess the impact of different UV filters and sunscreens, three UV filters — two organic (avobenzone and sulisobenzone) and one inorganic (titanium dioxide) — and commercial sunscreens, ‘eco-friendly’ sunscreens, and ‘mineral filters’ sunscreens were added at different concentrations to natural marine microbial (< 200 μm FSW) and prokaryotic (< 0.8 μm FSW) communities and monitored over 2d experiments. The distribution and dynamics of catalase-peroxidase and typical catalase genes were quantified by quantitative PCR (q-PCR) as indicators of oxidative stress. Catalase-peroxidase predominated over typical catalase in all samples. The response of the studied communities varied with the type and concentration of UV filters, as well as the type of sunscreen. The inorganic filter TIO₂ and the mineral sunscreen caused the greatest reduction in 16S rRNA gene abundance in both communities. Conversely, AVO filter and ECO sunscreens led to increased 16S rRNA gene abundances in microbial communities. These results highlight the need of assessing the effect of different UV filters and additional sunscreen ingredients to fully understand the environmental impact of solar sunscreens. Furthermore, significant increases in CP/16S rRNA and TC/16S rRNA ratios compared to the control, suggests that microorganisms exposed to these filters may develop enhanced defense mechanisms against reactive oxygen species (ROS). Catalase gene abundance assessment is a useful tool to assess the impact of these compounds on affected communities, however, further analysis is needed to clarify sunscreen effects on marine microorganisms and to develop new research hypotheses.