Dynamics of Suspended and Attached Aerobic Toluene Degraders in Small-Scale Flow-through Sediment Systems under Growth and Starvation Conditions

Mellage, Adrian; Eckert, Dominik; Grösbacher, Michael; Inan, Ayse Z.; Cirpka, Olaf A.; Griebler, Christian

doi:10.1021/es5058538

Cited by 24 publications

(32 citation statements)

References 48 publications

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“…Low maintenance yields are assumed to reflect that maintenance-induced microbial decay only partly covers the maintenance requirements. $ Based on Stolpovsky et al (2011Stolpovsky et al ( , 2016 and Mellage et al (2015).…”

Section: Functional Microbial Groupsmentioning

confidence: 99%

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Spatial Control of Carbon Dynamics in Soil by Microbial Decomposer Communities

Pagel

Kriesche

Uksa

et al. 2020

Front. Environ. Sci.

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Trait-based models have improved the understanding and prediction of soil organic matter dynamics in terrestrial ecosystems. Microscopic observations and pore scale models are now increasingly used to quantify and elucidate the effects of soil heterogeneity on microbial processes. Combining both approaches provides a promising way to accurately capture spatial microbial-physicochemical interactions and to predict overall system behavior. The present study aims to quantify controls on carbon (C) turnover in soil due to the mm-scale spatial distribution of microbial decomposer communities in soil. A new spatially explicit trait-based model (SpatC) has been developed that captures the combined dynamics of microbes and soil organic matter (SOM) by taking into account microbial life-history traits and SOM accessibility. Samples of spatial distributions of microbes at µm-scale resolution were generated using a spatial statistical model based on Log Gaussian Cox Processes which was originally used to analyze distributions of bacterial cells in soil thin sections. These µm-scale distribution patterns were then aggregated to derive distributions of microorganisms at mm-scale. We performed Monte-Carlo simulations with microbial distributions that differ in mm-scale spatial heterogeneity and functional community composition (oligotrophs, copiotrophs, and copiotrophic cheaters). Our modeling approach revealed that the spatial distribution of soil microorganisms triggers spatiotemporal patterns of C utilization and microbial succession. Only strong spatial clustering of decomposer communities induces a diffusion limitation of the substrate supply on the microhabitat scale, which significantly reduces the total decomposition of C compounds and the overall microbial growth. However, decomposer communities act as functionally redundant microbial guilds with only slight changes in C utilization. The combined statistical and process-based modeling approach derives distribution patterns of microorganisms at the mm-scale from microbial biogeography at microhabitat scale (µm) and quantifies the emergent macroscopic (cm) microbial and C dynamics. Thus, it effectively links observable process dynamics to the spatial control by microbial communities. Our study highlights a powerful approach that can provide further insights into the biological control of soil organic matter turnover.

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Section: Functional Microbial Groupsmentioning

confidence: 99%

“…Switching between dormant and active state was modeled as first-order process (Equation 16) based on the approach of Mellage et al (2015). Deactivation and reactivation rates are triggered by the concentration of dissolved monomers using a switching function (Equation 17).…”

Section: Fluxes and Functionsmentioning

confidence: 99%

Spatial Control of Carbon Dynamics in Soil by Microbial Decomposer Communities

Pagel

Kriesche

Uksa

et al. 2020

Front. Environ. Sci.

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“…That is, the biomass concentration has undergone first‐order decay for some time until the nitrate front arrives. In a more elaborate model accounting for transport of biomass, the aquifer would have been inoculated by floating cells prior to the arrival of the nitrate front, causing a more rapid increase of biomass concentration than in the current model (e.g., Mellage et al, ). However, the modeled time of establishing the biomass is only about 2 weeks at the inlet of the domain, which is small in comparison to the approximately eleven years of biomass being close to the maximal concentration.…”

Section: Resultsmentioning

confidence: 86%

“…Based on the experience of previous studies, we believe that we can simplify the system with the following assumptions: Microbes adapt to changing conditions on time scales that are shorter than the typical time scale of changes in aquifer‐scale nitrate transport. Intermediate periods of starvation may be overcome by dormancy (e.g., Mellage et al, ). Except for the initial establishment of a microbial anaerobic community, there may be no need to simulate the abundances of microbes explicitly.…”

Section: Theorymentioning

confidence: 99%

Accounting for the Decreasing Reaction Potential of Heterogeneous Aquifers in a Stochastic Framework of Aquifer‐Scale Reactive Transport

Loschko

Wöhling

Rudolph

et al. 2018

Water Resources Research

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Many groundwater contaminants react with components of the aquifer matrix, causing a depletion of the aquifer's reactivity with time. We discuss conceptual simplifications of reactive transport that allow the implementation of a decreasing reaction potential in reactive‐transport simulations in chemically and hydraulically heterogeneous aquifers without relying on a fully explicit description. We replace spatial coordinates by travel‐times and use the concept of relative reactivity, which represents the reaction‐partner supply from the matrix relative to a reference. Microorganisms facilitating the reactions are not explicitly modeled. Solute mixing is neglected. Streamlines, obtained by particle tracking, are discretized in travel‐time increments with variable content of reaction partners in the matrix. As exemplary reactive system, we consider aerobic respiration and denitrification with simplified reaction equations: Dissolved oxygen undergoes conditional zero‐order decay, nitrate follows first‐order decay, which is inhibited in the presence of dissolved oxygen. Both reactions deplete the bioavailable organic carbon of the matrix, which in turn determines the relative reactivity. These simplifications reduce the computational effort, facilitating stochastic simulations of reactive transport on the aquifer scale. In a one‐dimensional test case with a more detailed description of the reactions, we derive a potential relationship between the bioavailable organic‐carbon content and the relative reactivity. In a three‐dimensional steady‐state test case, we use the simplified model to calculate the decreasing denitrification potential of an artificial aquifer over 200 years in an ensemble of 200 members. We demonstrate that the uncertainty in predicting the nitrate breakthrough in a heterogeneous aquifer decreases with increasing scale of observation.

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“…Mellage et al . [] showed that even a starvation period of several months will not lead to a breakdown of the degradation capacity of a microbial community. The microbes can lie dormant for extended periods of time and then regain their full biodegradation potential within few hours after the end of the starvation period.…”

Section: General Conceptmentioning

confidence: 99%

Cumulative relative reactivity: A concept for modeling aquifer-scale reactive transport

et al. 2016

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We simulate aquifer‐scale reactive transport using an approach based on travel times and relative reactivity. The latter quantifies the intensity of the chemical reaction relative to a reference reaction rate with identical concentrations and can be interpreted as the strength of electron‐donor (or electron‐acceptor) release by the matrix, scaled by a reference release. In general, the relative reactivity is a spatially variable property reflecting the geology of the formation. In the proposed approach, we track the path of individual water parcels through the aquifer and evaluate the age of the water parcels and the relative reactivity integrated along their trajectories. By switching from spatial discretization to cumulative relative reactivity, advective‐reactive transport can be simulated by solving a single system of ordinary differential equations for each combination of concentrations in the inflow. We test the validity of the approach in a two‐dimensional test case of steady state groundwater flow and reactive transport involving aerobic respiration and denitrification. Here we compare steady state concentration distributions of the spatially explicit virtual truth, accounting for dispersive mixing, with the approximation based on cumulative relative reactivity and show that the errors introduced by neglecting dispersive mixing are minor if the target quantities are the mass fluxes crossing a control plane or being collected by a well. We further demonstrate the efficiency of the approach in a synthetic three‐dimensional case study. The proposed approach is computationally so efficient that ensemble runs to assess statistical distributions of concentration time series of reactive solutes become feasible, which is not practical with a spatially explicit model.

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Dynamics of Suspended and Attached Aerobic Toluene Degraders in Small-Scale Flow-through Sediment Systems under Growth and Starvation Conditions

Cited by 24 publications

References 48 publications

Spatial Control of Carbon Dynamics in Soil by Microbial Decomposer Communities

Spatial Control of Carbon Dynamics in Soil by Microbial Decomposer Communities

Accounting for the Decreasing Reaction Potential of Heterogeneous Aquifers in a Stochastic Framework of Aquifer‐Scale Reactive Transport

Cumulative relative reactivity: A concept for modeling aquifer-scale reactive transport

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