Ecological processes underpinning microbial community structure during exposure to subinhibitory level of triclosan

Abstract

Ecological processes shaping the structure and diversity of microbial communities are of practical importance for managing the function and resilience of engineered biological ecosystems such as activated sludge processes. This study systematically evaluated the ecological processes acting during continuous exposure to a subinhibitory level of antimicrobial triclosan (TCS) as an environmental stressor. 16S rRNA gene-based community profiling revealed significant perturbations on the community structure and dramatic reduction (by 20–30%) in species diversity/richness compared to those under the control conditions. In addition, community profiling determined the prevalence of the deterministic processes overwhelming the ecological stochasticity. Analysis of both community composition and phenotypes in the TCS-exposed communities suggested the detailed deterministic mechanism: selection of TCS degrading (Sphingopyxis) and resistant (Pseudoxanthomonas) bacterial populations. The analysis also revealed a significant reduction of core activated sludge members, Chitinophagaceae (e.g., Ferruginibacter) and Comamonadaceae (e.g., Acidovorax), potentially affecting ecosystem functions (e.g., floc formation and nutrient removal) directly associated with system performance (i.e., wastewater treatment efficiency and effluent quality). Overall, our study provides new findings that inform the mechanisms underlying the community structure and diversity of activated sludge, which not only advances the current understanding of microbial ecology in activated sludge, but also has practical implications for the design and operation of environmental bioprocesses for treatment of antimicrobial-bearing waste streams.

Bacterial ecotoxicity and shifts in bacterial communities associated with the removal of ibuprofen, diclofenac and triclosan in biopurification systems

“…Interestingly, species of this family have been determined as potential degraders of IBP, DCF, and naproxen . Oh et al (2019) also found enrichment of Xanthomonadaceae in TCS -amended activated sludge reactors, specifically of the genus Pseudoxanothomonas. Żur et al (2018) reported that Pseudoxanthomonas spadix BD-a59, a species with the ability to degrade all six BTEX (benzene, toluene, ethylbenzene, and o-, m-, and p-xylene) compounds, has a gene cluster with a high similarity with ibuprofen degradation genes ipfABDEF.…”

“…Recent studies have demonstrated that TCS is an environmental stressor, alters the community structure and reduces species diversity and richness (Clarke et al, 2019;Oh et al, 2019;Peng et al, 2019). The simultaneous treatment with the three PPCPs gave alpha diversity values generally lower than those obtained for IBP and DCF, and higher than for TCS alone, but not significantly different from the controls, except for a higher evenness after 7 days.…”

Repeatable ecological dynamics govern the response of experimental communities to antibiotic pulse perturbation

“…Understanding this response can be critical, among others, for rational therapeutics to mitigate unwanted effects on patient health caused by changes in the gut microbiota (e.g. Clostridioides difficile infection 6 ), management of waste water treatment to ensure the maintenance of key functionalities in bacterially driven processes 7 , and redesigning of agricultural practices to maintain microbiota contributing to crop health and productivity 8 .…”

Repeated introduction of micropollutants enhances microbial succession despite stable degradation patterns

“…The larger proportion of sensitive than tolerant taxa in all treatments suggested that the microbial community was not robust to the persistence of micropollutants in its surroundings. Noteworthily, two strictly tolerant genera across treatments were Sphingomonas and Hydrogenophaga (Table S4), which have been shown to be enriched in the BPA or TCS-contaminated environments (Oh et al, 2019;Zaborowska et al, 2020;Hagberg et al, 2021) and to produce enzymes capable of degrading different pollutants (Gao et al, 2019).…”