The influencing mechanisms of different characteristics of polystyrene microplastics on <i>Saccharomyces cerevisiae</i> : functional group, particle size and dosage

<b>ABSTRACT</b>Based on the well-documented hazards of microplastics and the importance and typicality of <i>Saccharomyces cerevisiae</i> (<i>S. cerevisiae</i>) in the environment, in this study, the influencing mechanisms of functional group, particle size and dosage of polystyrene microplastics (PS MPs) on <i>S. cerevisiae</i> were studied systematically. The results showed that compared with the bigger particle size and lower concentration of carboxylated PS MPs, the smaller particle size and higher concentration of aminated PS MPs had the most serious inhibition of the growth of <i>S. cerevisiae</i>, and their cell morphology was more abnormal, the more PS MPs attached to the yeast cells. The results of orthogonal experiment showed that the inhibitory effects of PS MPs on <i>S. cerevisiae</i> followed the order: functional groups > concentrations > particle sizes. Through the analysis of the antioxidant properties of <i>S. cerevisiae</i>, it was found that the activities of superoxide dismutase and catalase were first stimulated and then inhibited, and the concentrations of superoxide dismutase enzymes in the environment with bigger particle size and lower concentration of PS MPs was higher than that in the environment with smaller particle size and higher concentrations of PS MPs. catalase enzyme showed an opposite trend in particle sizes and a similar trend in concentrations. The concentrations of malondialdehyde increased with the increase of PS MPs concentrations and the decrease of particle sizes, indicating that PS MPs could induc<i>e S. cerevisiae</i> to produce a large amount of reactive oxygen species, resulting in severe oxidative damage to <i>S. cerevisiae</i>.