Responses of syntrophic microbial communities and their interactions with polystyrene nanoplastics in a microbial electrolysis cell

Basem S Zakaria; Seyed Mohammad Mirsoleimani Azizi; Biplob Kumar Pramanik; Faisal I Hai; Elsayed Elbeshbishy; Bipro Ranjan Dhar

doi:10.1016/j.scitotenv.2023.166082

Responses of syntrophic microbial communities and their interactions with polystyrene nanoplastics in a microbial electrolysis cell

Sci Total Environ. 2023 Dec 10:903:166082. doi: 10.1016/j.scitotenv.2023.166082. Epub 2023 Aug 5.

Authors

Basem S Zakaria¹, Seyed Mohammad Mirsoleimani Azizi¹, Biplob Kumar Pramanik², Faisal I Hai³, Elsayed Elbeshbishy⁴, Bipro Ranjan Dhar⁵

Affiliations

¹ Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
² School of Engineering, RMIT University, Melbourne, Australia.
³ Strategic Water Infrastructure Laboratory, School of Civil, Mining, Environmental and Architectural Engineering, University of Wollongong, Wollongong, Australia.
⁴ Civil Engineering, Toronto Metropolitan University, Toronto, Ontario, Canada.
⁵ Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada. Electronic address: bipro@ualberta.ca.

PMID: 37544438
DOI: 10.1016/j.scitotenv.2023.166082

Abstract

Microbial electrochemical technologies are promising for simultaneous energy recovery and wastewater treatment. Although the inhibitory effects of emerging pollutants, particularly micro/nanoplastics (MPs/NPs), on conventional wastewater systems have been extensively studied, the current understanding of their impact on microbial electrochemical systems is still quite limited. Microplastics are plastic particles ranging from 1 μm to 5 mm. However, nanoplastics are smaller plastic particles ranging from 1 to 100 nm. Due to their smaller size and greater surface area, they can penetrate deeper into biofilm structures and cell membranes, potentially disrupting their integrity and leading to changes in biofilm composition and function. This study first reports the impact of polystyrene nanoplastics (PsNPs) on syntrophic anode microbial communities in a microbial electrolysis cell. Low concentrations of PsNPs (50 and 250 μg/L) had a minimal impact on current density and hydrogen production. However, 500 μg/L of PsNPs decreased the maximum current density and specific hydrogen production rate by ∼43 % and ∼48 %, respectively. Exposure to PsNPs increased extracellular polymeric substance (EPS) levels, with a higher ratio of carbohydrates to proteins, suggesting a potential defense mechanism through EPS secretion. The downregulation of genes associated with extracellular electron transfer was observed at 500 μg/L of PsNPs. Furthermore, the detrimental impact of 500 μg/L PsNPs on the microbiome was evident from the decrease in 16S rRNA gene copies, microbial diversity, richness, and relative abundances of key electroactive and fermentative bacteria. For the first time, this study presents the inhibitory threshold of any NPs on syntrophic electroactive biofilms within a microbial electrochemical system.

Keywords: Electroactive biofilms; Emerging pollutants; Micro/nanoplastics; Microbial electrochemical technologies; Microbial syntrophy.