[Influence of Microplastics on the Development of Proteus Biofilm].

Currently, research on the effects of microplastics (MPs) in biofilms has mainly been focused on the mature biofilm communities, with a lack of sufficient details on the influence on different development stages of biofilms. Proteus and 1 μm polystyrene microplastics (PS-MPs), which are widely found in the environment, were selected as the research objects to explore the effects of microplastics on biofilms at different developmental stages. In our study, the effects of PS-MPs on biofilm biomass, extracellular polymer composition(EPS), and extracellular enzyme activity were investigated using an exposure test. Our results showed that the effect of PS-MPs on biofilms at different stages was similar, but the effect was significantly reduced with the development of biofilms. Biofilms at different development stages had different sensitivities to microplastics. In the reversible attachment stage, the no observed effect concentration (NOEC) of EPS composition, reactive oxygen species (ROS) production, and extracellular enzyme activity were significantly lower than those in other stages; however, the NOEC of total antioxidant capacity (T-AOC) and lactate dehydrogenase (LDH) activity were similar. This may be the result of ROS-mediated protein oxidation, which can be reduced but not completely eliminated by EPS in other stages of biofilm. This indicates that PS-MPs has a low toxic effect on biofilm.