May 9, 2022
Research Highlight

Examining the Ecological Assembly of Organic Matter and Microbes

Novel ecological measurement uncovered interactions between river corridor organic matter assemblages and microbial communities, highlighting potentially important microbial taxa and molecular formula types

Lake St Clair

The chemistry and biology of environmental systems (one of the reasons for color differences in waters) vary tremendously through space and time, and those variations have significant influences over the functioning of ecosystems, such as the production of greenhouse gases. New methods are needed to understand what drives this chemical and biological variation. This study developed a method to reveal the forces acting on individual chemical and biological species, instead of being limited to studying bulk assemblages of species. The method promises to reveal new mechanistic connections between the chemical and biological environment within complex environmental systems

The Science

Understanding how individual features within a community, like microbial or chemical species, impact the development of the overall community is an important question within ecology. By examining individual features, researchers can begin to identify those community or assemblage members that drive similarities across communities. To assist in this goal, scientists developed a novel ecological metric, called βNTIfeat,, which revealed that river corridor microbial communities are impacted by unknown lineages while organic matter is influenced by a variety of compounds.

The Impact

βNTIfeat will help researchers answer long-time questions about ecosystem functionality. For example, the application of βNTIfeat can help uncover a common group of microbes that significantly impact various river corridors at different local or global scales. As the dynamics of these microbes are incorporated into models, scientists can begin to generate predictions about how ecosystems may change amidst future disturbances (e.g., wildfires, climate change, etc.).


Evaluating how ecological communities develop and change is one of the primary goals of ecology. By examining processes which give rise to specific community configurations across varied conditions, researchers will have a better understanding of the fundamental principles that govern community structure and will be able to improve predictions. Unfortunately, comparatively fewer studies examine the impacts that individual features within a community or assemblage play on its overall structure. As part of this study, researchers developed a new metric, called βNTIfeat, that investigates the contributions features make within a community.

Researchers used βNTIfeat to evaluate feature-level ecological processes in a riverine ecosystem to reveal some key dynamics. First, the team observed that unclassified and uncultured microbial lineages often contribute to differences across the microbial communities; this observation suggests that these unclassified/uncultured lineages play an outsized role relative to their abundance. Secondly, the organic matter assemblages were often driven by nitrogen- and phosphorus-containing molecular formulas, indicating a potential connection to nitrogen/phosphorus-biogeochemical cycles. Finally, by relating the βNTIfeat values for microbes and molecular formulas using a network analysis, researchers determined that members of the microbial family Geobacteraceae often had coordinated contributions to ecological structure with both nitrogen- and phosphorous-containing molecular formulas. This observation suggests there is a complex network of ecological interactions across community types.


The initial experimental stages of this work were supported by the PREMIS Initiative at the Pacific Northwest National Laboratory with funding from the Laboratory Directed Research and Development Program at PNNL. The later stages of this work (e.g., data analysis, conceptual interpretation manuscript development) were supported by the Department of Energy Biological and Environmental Research program, as part of an Early Career Award to James C. Stegen at PNNL. A portion of the research was performed at the Environmental Molecular Sciences Laboratory, a DOE Office of Science user facility at PNNL.

Published: May 9, 2022

R. E. Danczak, et al. 2022. “Inferring the contribution of microbial taxa and organic matter molecular formulas to ecological assembly.” Front. Microbiol. 13, 803420. [DOI: 10.3389/fmicb.2022.803420/full]