Polystyrene microplastics of varying sizes and shapes induce distinct redox and mitochondrial stress responses in a Caco-2 monolayer

Abstract

a bacterial suspension, mineral medium, and MP. The algal growth inhibition assay was performed in sterile Erlenmeyer flasks (V r =100 mL) on a rotary shaker at 160 rpm and 25±2°C. The working flasks contained a suspension of microalgae, basal medium, and MP. Control flasks were also used to monitor the growth of the organisms and did not contain MP. The yeast toxicity test, based on the inhibition of sac-charose fermentation, was performed in hermetically-closed sterile glass bottles (working volume of 30 mL) at 28.0±0.1°C. The bottles contained yeast suspension, nutrient medium and MP. Bottles without MP were also used. Response surface modeling (RSM) was used to determine the effect of concentration (50, 250, 500, 750, and 1000 mg/L) and size of MP (200, 400, and 600 µm) on inhibition of each test organism. The inhibitions of all test organisms were determined by comparison the number of living cells of bacteria and microalgae (log CFU) and the volume of CO 2 gas produced in the yeast test with log CFU and volume obtained in the control. The highest effect of PS (14.74%), PVC (6.79%), PE (12.99%) and PS (100.00%) particles on Pseudomonas putida, Chlo-rella sp., Scenedesmus sp. and Saccharomycescerevisiae, respectively, was observed. By RSM and statistical analysis, it was found that the influencing factor for ecotoxicity of PS and PE on Pseudomonas putida and Scenedesmus sp. was concentration. Concentration and size had influence on the ecotoxicity of PVC and PS on Chlorella sp. and Saccharomyces cerevisiae, respectively. Overall, ecotoxicity increased with increasing concentration of MP and decreasing particle size of particles. However, with less than 10% inhibition, it can be concluded that MP do not significantly affect Chlorella sp. growth. Minor effects of MP were observed on the growth of Pseudomonas putida and Scenedesmus sp. and the most sensitive test organism to MP was Saccharomyces cerevisiae. References [1] ISO