EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Microscale physicochemical- and biological configurations regulate microbial biogeochemical processes and functionality

Gang Wang1, Kun Zhu1, David R. Johnson2,3, Chujin Ruan1,2, Josep Ramoneda2,4, Guram Gogia2,5, Hongyu Ran1, and Peixuan Zhang1
Gang Wang et al.
  • 1Department of Soil and Water Sciences, China Agricultural University, Beijing, China (
  • 2Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
  • 3Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
  • 4Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, USA
  • 5Department of Environmental Systems Science, Swiss Federal Institute of Technology, Zürich, Switzerland

The microscale spatiotemporal heterogeneities of physicochemical- and biological properties and their variational dynamics are key factors regulating microbial activity, soil quality and functionalities. Yet little is known about the underlying mechanisms and impacts on the functioning biogeochemical processes of the earth-surface ecosystems typically the soil-water-microbe-climate nexus. Employing microscale experiments, we illustrate how small-scale water and nutrient configurations as well as those of biological (populations) and chemical (such as O2 and pH) gradients regulate microbial interactions and functionality, and impacts on soil carbon (C) and nitrogen (N) cycling. We firstly use pairs of fluorescently labelled bacterial strains and a hyphae-forming fungal strain that expand together across a nutrient-amended surface, and show that flagellar motility drives bacterial dispersal along the hyphal network, which counteracts the purifying effects of ecological drift at the expansion frontier and thereby increases the spatial intermixing and extent of range expansion of the bacterial strains. We further demonstrate that fungal hyphae are important regulators of bacterial diversity and promote plasmid-mediated functional novelty during range expansion in an interaction-independent manner. In addition, we employed a soil column experiment and illustrated that sufficient labile carbon from plant residues such as straw induced fast O2 consumption with microoxic development in the straw-soil interfaces. In the meantime, the porous structure of straw materials could enhance O2 diffusive inputs in the core area, and subsequently formed a a concentric ring-like microoxic area around the straw patch. Such enriched oxic-microoxic transient zones would induce nitrification coupled denitrification, which led to the high N2O emissions. Additionally, the microbial degradation of straw resulted in a pulse decline of soil pH, which possibly inhibited the N2O reductases, yielding enhanced N2O emissions. These results contribute to a better understanding of the driving factors for microbial interactions and possible impacts of soil key element (such as C and N) cycling.

How to cite: Wang, G., Zhu, K., R. Johnson, D., Ruan, C., Ramoneda, J., Gogia, G., Ran, H., and Zhang, P.: Microscale physicochemical- and biological configurations regulate microbial biogeochemical processes and functionality, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11645,, 2023.