Functional stability of microbial ecosystems
Approach to test the impact of changing environmental conditions on the dispersal of bacterial populations.Transfer of concepts from general to microbial ecologyMicrobes live in spatially structured and often diverse microbial communities. The spatial structure and interactions between community members are supposed to be important for community stability. However, the absence of a theoretical framework makes it difficult to bundle and synthesize existing knowledge and to explain changes in community behavior and stability of diverse assemblages. We suggested to adapt the concept of Asociational Effects from plant ecology, to better understand the link between ecological interactions, spatial arrangement, and stability in microbial communities. |
Perspective article 
Associational Effects in the Microbial Neighborhood Worrich et al. 2019, ISME J |
Stress imposed by drought and salinityDrought and salinity are major threats associated with climate change. Such stresses can have severe impacts on the activity of microorganisms, which in turn can negatively affect the provision of ecosystem services. In contaminated soils, for example, bacteria contribute to the removal of pollutants thereby preventing their leaching into the groundwater. Efficient removal requires that bacteria are active and get access to the contaminants. Using synthetic microbial ecosystems we have shown that reduced matric and osmotic potentials ceased bacterial motility and in consequence slowed down biodegradation. The presence of dispersal networks (e.g. fungal mycelia) improved the functional resistance of the system by allowing for colonisation under stress conditions. We also showed that fungal mycelia can boost bacterial activity in dry and oligotrophic environments by providing them with water and nutrients. Bacterial-fungal interactions may thus be a key factor for the stability of stressed ecosystems. |
Research article 
Mycelium-Like Networks Increase Bacterial Dispersal, Growth, and Biodegradation in a Model Ecosystem at Various Water Potentials. Worrich et al. 2016, Appl Environ Microbiol |
Research article
Bacterial Dispersal Promotes Biodegradation in Heterogeneous Systems Exposed to Osmotic Stress Worrich et al. 2016, Front Microbiol |
Research article
Mycelium-mediated Transfer of Water and Nutrients Stimulates Bacterial Activity in Dry and Oligotrophic Environments Worrich et al. 2017, Nat Comm |
Testing the effects of disturbances in virtual and synthetic microbial ecosystemsWhile drought and salinity are more continuous events relative to the life span of a bacterium, microbial ecosystems are also subject to discrete events affecting populations, resources or the physical environment. The recovery of microbial ecosystems from such disturbances is a pressing question as global change is anticipated to increase the frequency and intensity of disturbances. However, mechanistic understanding of the factors governing the recovery of microbial ecosysems is missing. Using an ecological model of bacterial growth, dispersal, and substrate consumption, we tested the impact of disturbance configuration, intensity and frequency on the functional stability of biodegradation as an exemplary soil function. Thereby, we were able to show that spatial processes (substrate diffusion and dispersal) are decisive for the temporal recovery dynamics and that disturbance fragmentation and intensity determine the thresholds beyond which functional collapse can occur. |
Disturbance patterns with different fragmentations (Picture: Sara König)Research article Modelling functional resilience of microbial ecosystems: Analysis of governing processes; König et al. 2017, Environ Modell Softw Research article Functional resistance to recurrent spatially heterogeneous disturbances is facilitated by increased activity of surviving bacteria in a virtual ecosystem; König et al. 2018, Research article Spatiotemporal disturbance characteristics determine functional stability and collapse risk of simulated microbial ecosystems; König et al. 2018, Sci Rep |
Perspective article 
Prospects for Integrating Disturbances, Biodiversity and Ecosystem Functioning Using Microbial Systems Banitz et al. 2020, Front Ecol Evol |