Wastewater constituents impact biofilm microbial community in receiving streams

Manu Tamminen,Jenny Spaak,Ahmed Tlili,Rik Eggen,Christian Stamm,Katja Räsänen

doi:10.1016/j.scitotenv.2021.151080

Abstract

Microbial life in natural biofilms is dominated by prokaryotes and microscopic eukaryotes living in dense association. In stream ecosystems, microbial biofilms influence primary production, elemental cycles, food web interactions as well as water quality. Understanding how biofilm communities respond to anthropogenic impacts, such as wastewater treatment plant (WWTP) effluent, is important given the key role of biofilms in stream ecosystem function.Here, we implemented 16S and 18S rRNA gene sequencing of stream biofilms upstream (US) and downstream (DS) of WWTP effluents in four Swiss streams to test how bacterial and eukaryotic communities respond to wastewater constituents. Stream biofilm composition was strongly affected by geographic location – particularly for bacteria. However, the abundance of certain microbial community members was related to micropollutants in the wastewater – among bacteria, micropollutant-associated members were found e.g. in Alphaproteobacteria, and among eukaryotes e.g. in Bacillariophyta (algal diatoms). This study corroborates several previously characterized responses (e.g. as seen in diatoms), but also reveals previously unknown community responses – such as seen in Alphaproteobacteria. This study advances our understanding of the ecological impact of the current wastewater treatment practices and provides information about potential new marker organisms to assess ecological change in stream biofilms.

Highlights

Microbial communities perform fundamentally important biological functions within organisms, and across ecosystems (Bardgett and van der Putten, 2014; Donaldson et al, 2015; Fuhrman et al, 2015; Grice and Segre, 2011; Guttman et al, 2014; Kwong and Moran, 2016)
We implemented 16S and 18S rRNA gene sequencing of stream biofilms upstream (US) and downstream (DS) of wastewater treatment plant (WWTP) effluents in four Swiss streams to test how bacterial and eukaryotic communities respond to wastewater constituents
18S) revealed that these stream biofilm communities are most commonly dominated by the bacterial phyla Bacteroidetes and Proteobacteria, and the eukaryotic phyla Chlorophyta, Ochrophyta and Metazoa (Fig. 1)

Summary

Introduction

Microbial communities perform fundamentally important biological functions within organisms (i.e. host-associated microbiomes), and across ecosystems (Bardgett and van der Putten, 2014; Donaldson et al, 2015; Fuhrman et al, 2015; Grice and Segre, 2011; Guttman et al, 2014; Kwong and Moran, 2016). Microbial life is dominated by dense biofilms consisting of bacteria, archaea and microscopic eukaryotes. These biofilms form the basis of the stream food webs by performing crucial functions, such as elemental cycles, ecosystem respiration, primary production and maintenance of good water quality (Aristi et al, 2015; Battin et al, 2016). Stream biofilms are capable of resisting invasions by microorganisms to some degree and have a central role in attenuating microbiological changes in stream water (Battin et al, 2007, 2003; Carles et al, 2021). Stream biofilm composition can be influenced by wastewater-born microorganisms (Carles et al, 2021). Stream biofilms can be strongly affected by human activities such as agriculture, industry or wastewater discharge – resulting in potential alterations of the ecological functions they provide (Besemer et al, 2009)

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Results

Conclusion