Single brand tire wear particles promote toxin-producing of an invasive cyanobacterium.

Tire wear particles (TWPs), as newly emerging pollutants, frequently co-occur with potentially toxic cyanobacteria in eutrophic waters. However, it is unknown how these new pollutants affect ecology of mass bloom-forming cyanobacteria. Here, we compared single brand and mixed brand TWPs how to affect the invasive and toxic cyanobacterium Raphidiopsis raciborskii. Our results demonstrated that, in the short-term (2 days), single- and mixed-brand TWPs had no significant influence on cyanobacterial growth, whereas single-brand TWPs and large-sized mixed-brand TWPs at high doses significantly reduced photosynthetic pigments. In the long-term (30 days), mixed-brand TWPs inhibited cyanobacterial growth and photosynthetic pigments synthesis more strongly than single-brand TWPs, especially exposed to high doses of large-sized mixed-brand TWPs (growth inhibitory effect up to about 80%). In addition, prolonged exposure to high-dose single-brand TWPs resulted in a marked reduction of photosynthetic activity. Moreover, high doses of large-sized single-brand TWPs significantly promoted toxin production by R. raciborskii. In contrast, mixed-brand TWPs had no significant effect on cyanobacterial toxin production. Our findings provide novel insights into potential risks for environmental and human health via the interaction between toxigenic R. raciborskii and different types of TWPs.