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

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

mSystems ◽

10.1128/msystems.00471-20 ◽

2020 ◽

Vol 5 (4) ◽

Cited By ~ 1

Author(s):

Ezequiel Santillan ◽

Florentin Constancias ◽

Stefan Wuertz

Keyword(s):

Community Structure ◽

Microbial Communities ◽

Community Assembly ◽

Temporal Dynamics ◽

Functional Gene ◽

Functional Genes ◽

Rrna Gene ◽

Α Diversity ◽

Press Disturbance ◽

Joint Evaluation

ABSTRACT 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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EFFECT OF ORGANIC CARBON LOADING (OCL) ON SIMULTANEOUS NH4+-N AND Mn2+ REMOVAL IN DRINKING WATER USING A BAF SYSTEM

Environmental Engineering and Management Journal ◽

10.30638/eemj.2011.236 ◽

2011 ◽

Vol 10 (11) ◽

pp. 1733-1742 ◽

Cited By ~ 7

Author(s):

Hassimi Abu Hasan ◽

Siti Rozaimah Sheikh Abdullah ◽

Siti Kartom Kamarudin ◽

Noorhisham Tan Kofli

Keyword(s):

Drinking Water ◽

Organic Carbon ◽

Organic Carbon Loading ◽

Carbon Loading

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Biofilm thickness matters: Deterministic assembly of different functions and communities in nitrifying biofilms

10.1101/416701 ◽

2018 ◽

Cited By ~ 1

Author(s):

Carolina Suarez ◽

Maria Piculell ◽

Oskar Modin ◽

Silke Langenheder ◽

Frank Persson ◽

...

Keyword(s):

Wastewater Treatment ◽

Environmental Factors ◽

Community Composition ◽

Community Assembly ◽

Treatment Plant ◽

Rrna Gene ◽

Strong Impact ◽

Biotechnological Applications ◽

Biofilm Thickness ◽

Microbial Biofilms

ABSTRACTMicrobial biofilms are important in natural ecosystems and in biotechnological applications. Biofilm architecture influences organisms’ spatial positions, who their neighbors are, and redox gradients, which in turn determine functions. We ask if and how biofilm thickness influences community composition, architecture and functions. But biofilm thickness cannot easily be isolated from external environmental factors. We designed a metacommunity system in a wastewater treatment plant, where either 50 or 400 µm thick nitrifying biofilms were grown simultaneously on biofilm carriers in the same reactor. Model simulations showed that the 50 µm biofilms could be fully oxygenated whereas the 400 µm biofilms contained anaerobic zones. The 50 and 400 µm biofilms developed significantly different communities. due to deterministic factors were stronger than homogenizing dispersal forces in the reactor, despite the fact that biofilms experienced the same history and external conditions. Relative abundance of aerobic nitrifiers was higher in the 50 µm biofilms, while anaerobic ammonium oxidizers were more abundant in the 400 µm biofilms. However, turnover was larger than the nestedness component of between-group beta-diversity, i.e. the 50 µm biofilm was not just a subset of the thicker 400 µm biofilm with reduced taxa richness. Furthermore, the communities had different nitrogen transformation rates. The study shows that biofilm thickness has a strong impact on community composition and ecosystem function, which has implications for biotechnological applications, and for our general understanding of biofilms.IMPORTANCEMicroorganisms colonize all surfaces in water and form biofilms. Diffusion limitations form steep gradients of energy and nutrient sources from the water phase into the deeper biofilm parts, influencing community composition through the biofilm. Thickness of the biofilm will affect diffusion gradients, and is therefore presumably important for biofilm composition. Since environmental factors determine thickness, studies of how thickness influences biofilm functions and community assembly, have been difficult to perform. We studied biofilms for wastewater treatment with fixed thicknesses of 50 and 400 µm during otherwise similar conditions and history. Despite growing in the same wastewater reactor, 16S rRNA gene sequencing and confocal microscopy showed the formation of two different communities, performing different ecosystem functions. Using statistical methods, we show for the first time, how biofilm thickness influences community assembly. The results help our understanding of the ecology of microbial biofilms, and in designing engineered systems based on ecological principles.

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Press xenobiotic disturbance favors deterministic assembly with a shift in function and structure of bacterial communities in sludge bioreactors

10.1101/2020.10.15.341966 ◽

2020 ◽

Author(s):

Ezequiel Santillan ◽

Hari Seshan ◽

Stefan Wuertz

Keyword(s):

Community Structure ◽

Bacterial Communities ◽

Temporal Dynamics ◽

Treatment Plant ◽

Amplicon Sequencing ◽

Rrna Gene ◽

Batch Reactors ◽

Function Structure ◽

Community Function ◽

And Function

AbstractDisturbance is thought to affect community assembly mechanisms, which in turn shape community structure and the overall function of the ecosystem. Here, we tested the effect of a continuous (press) xenobiotic disturbance on the function, structure, and assembly of bacterial communities within a wastewater treatment system. Two sets of four-liter sequencing batch reactors were operated in triplicate with and without the addition of 3-chloroaniline for a period of 132 days, following 58 days of acclimation after inoculation with sludge from a full-scale treatment plant. Temporal dynamics of bacterial community structure were derived from 16S rRNA gene amplicon sequencing. Community function, structure and assembly differed between press disturbed and undisturbed reactors. Temporal partitioning of assembly mechanisms via phylogenetic and non-phylogenetic null modelling analysis revealed that deterministic assembly prevailed for disturbed bioreactors, while the role of stochastic assembly was stronger for undisturbed reactors. Our findings are relevant because research spanning various disturbance types, environments and spatiotemporal scales is needed for a comprehensive understanding of the effects of press disturbances on assembly mechanisms, structure, and function of microbial communities.Graphical abstract

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