Microbial Communities in Full-Scale Wastewater Treatment Systems Exhibit Deterministic Assembly Processes and Functional Dependency over Time

Abstract

Microbial communities constitute the core component of biological wastewater treatment processes. We conducted a meta-analysis based on the 16S rRNA gene of temporal samples obtained from diverse full-scale activated sludge and anaerobic digestion systems treating municipal and industrial wastewater (collected in this study and published previously) to investigate their community assembly mechanism and functional traits over time, which are not currently well understood. The influent composition was found to be the main driver of the microbial community’s composition, and relatively large proportions of specialist (26.1% and 18.6%) and transient taxa (67.2% and 68.1%) were estimated in both systems. Deterministic processes, especially homogeneous selection events (accounting for >53.8% of assembly events), were consistently identified as the dominant microbial community assembly mechanisms in both systems over time. Significant and strong correlations (Pearson’s r = 0.51–0.92) were detected between the dynamics of the temporal community and the functional compositions in both systems, which suggests functional dependency. In contrast, the occurrence of sludge bulking and foaming in the activated sludge system led to an increase in stochastic assembly processes (i.e., limited dispersal and undominated events), a shift toward functional redundancy and less community diversity, a decreased community niche breadth index, and a more compact co-association network. This study illustrates that the mechanism of microbial community assembly and functional traits over time can be used to diagnose system performance and provide information on potential system malfunction.

Labile carbon feedstocks trigger a priming effect in anaerobic digestion: An insight into microbial mechanisms

“…A priming effect is often associated with microbial community turnover (Kuzyakov, 2010). Functional dependence in AD highlights the close relationship between microbial community turnover and AD performance changes (Yu et al, 2021). In this study, the strongest promotion of CH 4 production by the labile carbon occurred shortly after feedstock addition, well aligning with the enhanced deterministic turnover of the active microbial communities in the digestate (Fig.…”

“…The dominance of deterministic processes in microbial community turnover is often observed in bioreactors (Yu et al, 2021), and positively correlated with bioreactor performance (Lin et al, 2017;Zhang et al, 2019). This is because the success of AD is grounded in cooperation among microorganisms involved in different functions (hydrolysis, acidogenesis, acetogenesis and methanogenesis), which necessitates orderliness and/or organization of microbial communities and functions, usually aligning with deterministic processes in microbial community turnover.…”

“…During each feedstock addition (swine manure), there were not only nutrient inputs, but also potential disturbances from (1) the changes in the bioreactor physicochemical features and (2) the input of new microorganisms. This disturbance probably breaks microbial niche balances, and, thus, may result in chaos in microbial cooperation and activity, and increase stochastic processes in community turnover, finally declining AD performance (Lin et al, 2017;Yu et al, 2021;Zhang et al, 2019). Therefore, microbial community deterministic turnover after feedstock addition played pivotal roles in CH 4 production.…”

Niche differentiation drives microbial community assembly and succession in full-scale activated sludge bioreactors

“…Thus, it is essential to understand the structure and assembly of these communities to ensure an optimal operation of WWTPs 3 . Most studies describing WWTP microbial communities are focused on taxonomic exploration; however, there is a need to assess which mechanisms explain the patterns arising from the interactions between taxa that shape these communities in time and space 4 , 5 .…”

Antimicrobial Resistance in New Zealand—A One Health Perspective

“…Antimicrobial resistance (AMR) is a growing, serious global threat to human, animal and environmental health associated with antimicrobial use in humans and animals and waste discharges, including pharmaceutical wastewater [ 1 , 2 , 3 ]. AMR describes the adaptation of microorganisms, including bacteria, viruses, fungi and parasites, to grow in the presence of concentrations of antimicrobial agents that previously prevented growth or were lethal [ 4 , 5 ].…”