Sustained organic loading disturbance favors nitrite accumulation in bioreactors with variable resistance, recovery and resilience of nitrification and nitrifiers

Santillan, Ezequiel; Phua, W. X.; Constancias, Florentin; Wuertz, Stefan

doi:10.1101/605733

Cited by 3 publications

(15 citation statements)

References 86 publications

(95 reference statements)

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“…Sequencing batch reactors (SBR) with a 5-L working volume were inoculated with activated sludge from a wastewater treatment plant (WWTP) in Singapore and operated on continuous 12-h cycles with intermittent aeration. The experimental setup was detailed elsewhere [44]. Briefly, four reactors were acclimated to laboratory conditions for 53 days while being fed a complex synthetic wastewater containing a variety of carbon and nitrogen compounds.…”

Section: Experimental Designmentioning

confidence: 99%

“…Sludge biomass was measured as total suspended solids (TSS) twice a week, after which biomass wastage was done to target 1500 mg L -1 of TSS in order to control the food-to-biomass ratio (F:M) (Table S1). See [44] for detailed information of the source WWTP, inoculum collection, feed preparation, sludge sampling, analytical methods, DNA extractions,…”

Section: Experimental Designmentioning

confidence: 99%

“…Taxonomy was assigned using the SILVA database (v.132) [49]. See [44] for further details including rarefaction curves.…”

Section: S Rrna Gene Metabarcoding and Reads Processingmentioning

confidence: 99%

“…We employed the four databases available with the rate of assigned/total reads being the highest for the IP2G database (52%), followed by SEED (21%), COG (15%), and KEGG (13%). See [44] for more details including rarefaction curves.…”

Section: Metagenomics Sequencing and Reads Processingmentioning

confidence: 99%

“…Ecosystem function dynamics were described in detail elsewhere [44]. In short, there was a clear distinction between low and high organic loading reactors, in terms of nitrification and organic carbon removal, with the press disturbed reactors displaying partial nitrification with high NO2-N and COD concentrations in the effluent (Fig.…”

Section: Dynamics Of Ecosystem Functionsmentioning

confidence: 99%

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Press disturbance unveils different community structure, function and assembly of bacterial taxa and functional genes in mesocosm-scale bioreactors

Santillan

Constancias

Wuertz

2019

Preprint

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Sustained perturbations, or press disturbances, are of interest in microbial ecology as they can drive systems to alternative stable states. Here, we tested the effect of a sustained doubling of organic carbon loading on structure, assembly and function of bacterial communities. Two sets of replicate 5-liter sequencing batch reactors were operated at two different organic carbon loading levels (323 and 629 mg COD L -1 ) for a period of 74 days, following 53 days of acclimation after inoculation with sludge from a full-scale treatment plant. Temporal dynamics of community taxonomic and functional gene structure were derived from metagenomics and 16S rRNA gene metabarcoding data. Assembly mechanisms were assessed through a mathematical null model on the effective bacterial turnover expressed as a proportion of total bacterial diversity. Disturbed reactors exhibited different community function, structure and assembly compared to the undisturbed reactors. Bacterial taxa and functional genes showed dissimilar alphadiversity and community assembly patterns. Deterministic assembly mechanisms were generally stronger in disturbed reactors, associated with common taxa. Stochastic assembly was more important for functional genes and was driven by rare genes. We urge caution when assessing microbial community assembly mechanisms, as results can vary depending on the approach.

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Section: Experimental Designmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

“…Taxonomy was assigned using the SILVA database (v.132) [49]. See [44] for further details including rarefaction curves.…”

Section: S Rrna Gene Metabarcoding and Reads Processingmentioning

confidence: 99%

Section: Metagenomics Sequencing and Reads Processingmentioning

confidence: 99%

Section: Dynamics Of Ecosystem Functionsmentioning

confidence: 99%

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Press disturbance unveils different community structure, function and assembly of bacterial taxa and functional genes in mesocosm-scale bioreactors

Santillan

Constancias

Wuertz

2019

Preprint

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Metagenomics and Metatranscriptomics Suggest Pathways of 3-Chloroaniline Degradation in Wastewater Reactors

Seshan

Santillan

Constancias

et al. 2021

Preprint

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Biological wastewater treatment systems are often affected by major shifts in influent quality, including the input of various toxic chemicals. Yet the mechanisms underlying adaptation of activated sludge process performance when challenged with a sustained toxin input have not been studied in a controlled and replicated experiment. Three replicate bench-scale bioreactors were subjected to a chemical disturbance in the form of 3-chloroaniline (3-CA) input over 132 days, following an acclimation period of 58 days, while three control reactors received no 3-CA input. The nitrification process was initially affected by 3-CA input; yet all three treatment reactors evolved to biologically degrade 3-CA within three weeks of the experiment, resulting in partial nitrification recovery. 16S rRNA amplicon sequencing revealed that ammonia oxidizers were initially impacted by 3-CA, and a new ammonia oxidizing community emerged with the onset of 3-CA degradation. Combining process and microbial community data from amplicon sequencing with potential functions gleaned from assembled metagenomics and metatranscriptomics data, 3-CA degradation was shown to likely occur via a phenol monooxygenase followed by ortho-cleavage of the aromatic ring. The relative abundance of genera Gemmatimonas, Saprospiraceae OLB8 and Taibaiella correlated significantly with 3-CA degradation. This study demonstrated the impact of a sustained stress on the activated sludge community and wastewater treatment process and its subsequent recovery. Using a combination of techniques in a controlled and replicated experiment, we showed that microbial communities can evolve degradative capacity following a sustained xenobiotic input, specific functions like nitrification can fully or partially recover and targeted culture-independent approaches can be used to elucidate the mechanisms of adaptation.

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Press Disturbance Alters Community Structure and Assembly Mechanisms of Bacterial Taxa and Functional Genes in Mesocosm-Scale Bioreactors

2020

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Press disturbances are of interest in microbial ecology, as they can drive microbial communities to alternative stable states. However, the effect of press disturbances in community assembly mechanisms, particularly with regard to taxa and functional genes at different levels of abundance (i.e., common and rare), remains largely unknown. Here, we tested the effect of a continuous alteration in substrate feeding scheme on the structure, function, and assembly of bacterial communities. Two sets of replicate 5-liter sequencing batch reactors were operated at two different organic carbon loads for a period of 74 days, following 53 days of acclimation after inoculation with sludge from a full-scale treatment plant. Temporal dynamics of community taxonomic and functional gene structure were derived from metagenomics and 16S rRNA gene metabarcoding data. Disturbed reactors exhibited different community function, structure, and assembly compared to undisturbed reactors. Bacterial taxa and functional genes showed dissimilar α-diversity and community assembly patterns. Deterministic assembly mechanisms were generally stronger in disturbed reactors and in common fractions compared to rare ones. Function quickly recovered after the disturbance was removed, but community structure did not. Our results highlight that functional gene data from metagenomics can indicate patterns of community assembly that differ from those obtained from taxon data. This study reveals how a joint evaluation of assembly mechanisms and community structure of bacterial taxa and functional genes as well as ecosystem function can unravel the response of complex microbial systems to a press disturbance. IMPORTANCE Ecosystem management must be viewed in the context of increasing frequencies and magnitudes of various disturbances that occur at different scales. This work provides a glimpse of the changes in assembly mechanisms found in microbial communities exposed to sustained changes in their environment. These mechanisms, deterministic or stochastic, can cause communities to reach a similar or variable composition and function. For a comprehensive view, we use a joint evaluation of temporal dynamics in assembly mechanisms and community structure for both bacterial taxa and their functional genes at different abundance levels, in both disturbed and undisturbed states. We further reverted the disturbance state to contrast recovery of function with community structure. Our findings are relevant, as very few studies have employed such an approach, while there is a need to assess the relative importance of assembly mechanisms for microbial communities across different spatial and temporal scales, environmental gradients, and types of disturbance.

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Sustained organic loading disturbance favors nitrite accumulation in bioreactors with variable resistance, recovery and resilience of nitrification and nitrifiers

Cited by 3 publications

References 86 publications

Press disturbance unveils different community structure, function and assembly of bacterial taxa and functional genes in mesocosm-scale bioreactors

Press disturbance unveils different community structure, function and assembly of bacterial taxa and functional genes in mesocosm-scale bioreactors

Metagenomics and Metatranscriptomics Suggest Pathways of 3-Chloroaniline Degradation in Wastewater Reactors

Press Disturbance Alters Community Structure and Assembly Mechanisms of Bacterial Taxa and Functional Genes in Mesocosm-Scale Bioreactors

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