Scanning Electron Microscopy and Metabolite Measurement Revealed the Stress Mechanism of PS-COOH Microplastics on Rhodotorula mucilaginosa AN5

Abstract Microplastics in the marine environment have been paid more and more attention by researchers, and the impact of these substances on marine microorganisms can not be ignored. This study aims to pay attention to the effect and mechanism of microplastics (80 nm PS-COOH) on Antarctic marine yeast, Rhodotorula mucilaginosa AN5. In our work, Scanning Electron Microscopy (SEM) was used to observe the morphology of yeast cells under microplastic stress, and metabolite analysis was used to explore the possible mechanism of yeast cell damage. The results showed that: (1) a certain concentration of PS-COOH could inhibit 40% growth of yeast cells and destroy the cell morphology. (2) Physiological and biochemical changes showed that under PS-COOH stress, the level of reactive oxygen species (ROS), malondialdehyde (MDA) content and the activities of antioxidant enzymes such as catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) of R. mucilaginosa AN5 increased from 34–66%. It can be guessed that yeast can eliminate excess ROS in cells by the activity of oxidative kinases increased and maintain the balance of reactive oxygen species in cells.