Characterizing the Biofilm of Microplastics Incubated in River Water and Treated Wastewater Effluent
Citation:
Brown, S., S. Eytcheson, H. Wu, C. Nietch, P. Weaver, J. Darling, S. Purucker, AND M. Molina. Characterizing the Biofilm of Microplastics Incubated in River Water and Treated Wastewater Effluent. 2024 American Society for Microbiology Annual Meeting, Atlanta, GA, June 13 - 17, 2024.
Impact/Purpose:
Because the biofilm surrounding microplastics (plastisphere) is known to accumulate pathogens and bacteria with antibiotic resistance genes (ARGs), microplastics can act as a carrier of microbial pathogens and antimicrobial resistance in the environment. Since wastewater treatment plants (WWTPs) can be a source of microplastic pollution entering freshwater environments, along with antibiotics and other contaminants of emerging concern, studying the role of microplastics as carriers of contaminants in environmental waters is relevant to assess public health risk.
Description:
Microplastics (MPs) in aquatic environments accumulate a biofilm known as the plastisphere, a microbial community unique from that of the surrounding water and from biofilms that form on natural substrates. The plastisphere is known to accumulate pathogens and bacteria with antibiotic resistance genes (ARGs); microplastics can therefore act as a carrier of pathogens and ARGs in the environment. Since wastewater treatment plants (WWTPs) can be a source of microplastic pollution entering freshwater environments, along with antibiotics and other contaminants of emerging concern, we compared the biofilm of MPs in river water to MPs in river water amended with effluent from a WWTP. The objectives of this study were to 1) examine bacterial community development on microplastics over a 10-week period; 2) determine whether plastic type and water source influence biofilm composition; and 3) identify potential pathogens present in the plastisphere. Results of 16S amplicon-based sequencing showed that bacterial community composition on microplastics changed significantly over time, with communities displaying increased diversity at the 10-week timepoint. While microplastics composed of different plastic types did not display significant differences in bacterial community composition, microplastics incubated in river water and treated wastewater developed distinct bacterial communities. To identify bacteria that were differentially abundant between these treatments, we conducted a differential abundance analysis using DESeq2. The identification of specific bacterial genera (for example Pseudomonas, Mycobacterium, and Hyphomicrobium) that were substantially more abundant on microplastics incubated in treated wastewater indicates that the presence of wastewater effluent can influence the composition of the plastisphere.