Limited bisphenol A (BPA) degradation acceleration by pre-acclimating microplastic biofilms with BPA in natural lake water

Abstract

Background: Bisphenol A (BPA) and microplastics are prevalent in aquatic environments. Microplastic biofilms play a crucial role in the environmental degradation of BPA, but related research is lacking. We designed experiments to investigate the effect of BPA on microplastic biofilms and the effect of pre-acclimating biofilms on BPA degradation. Results: Even at low concentrations (0.1 mg L^-1), BPA significantly reduced microplastic biofilm biomass (P < 0.05). High-throughput 16S rRNA sequencing revealed that BPA altered biofilm diversity, as evidenced by changes in Chao-1 and Shannon indices. The primary phyla in the microplastic biofilm included Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. On the 7^th day of biofilm formation, the dominant bacterial genus shifted from Ohtaekwangia to Bdellovibrio in groups with BPA treatment, and the relative abundance of Bdellovibrio reached 4.32% ± 5.34%. On the 14^th day, Methylobacillus significantly increased in all treatments compared with the 7^th day (P < 0.05). Adonis analysis demonstrated that the metabolic composition of the bacterial community also changed significantly (P < 0.05). BPA (0.1 mg L^-1) pre-acclimation of microplastic biofilms led to a significant increase in the amount of BPA-degrading bacteria with no significant effect on BPA degradation efficiency. After 7 days, the BPA removal rate in high-concentration microplastic treatments (1600 mg L^-1) reached > 90%. Conclusions: Biofilms significantly increased the BPA degradation rate by 174.78% to 889.25% on the third day, indicating that the biofilm accelerates BPA degradation efficiency in the short term. Our findings provide a foundation for further understanding the environmental risks associated with the coexistence of bisphenols and microplastics.