The Impact of Pore-Size Heterogeneities on the Spatiotemporal Variation of Microbial Metabolic Activity in Porous MediaStolpovsky, Konstantin1; Gharasoo, Mehdi2; Thullner, Martin1,2Soil Science: February 2012 - Volume 177 - Issue 2 - p 98–110 doi: 10.1097/SS.0b013e318241105d Technical Article Abstract Author Information Natural porous media such as soils or aquifers are characterized by various pore-scale heterogeneities. This includes the temporal variability of substrate supply and the spatial heterogeneity of pore sizes. As a consequence, microbial growth conditions in natural porous medium environments may differ from typical laboratory setups used to study microbial behavior. Pore-size heterogeneities and the resulting transport regime can lead to highly complex distribution patterns of substrates and corresponding microbial growth conditions including the frequent occurrence of stress periods for the microbial population. Microorganisms can respond to such stress periods by switching from an active into an inactive or dormant state, and the corresponding microbial abundance and dynamics may exhibit rather complex temporal and spatial patterns. This study applies an extended modeling concept for the growth and degradation activity of microbial species able to switch between two different physiological states. The concept is implemented into a pore network model that allows simulating the changes in microbial growth conditions in heterogeneous porous media. The model is used to study the impact of pore-size heterogeneities on the distribution and activity of a bacterial community consisting of two competing species. Simulation results show that such pore-scale heterogeneity has a strong impact on bacterial abundance and activity, creating a complex structure of microbial niches. This leads to an increased coexistence of microbial species at both the microscale and the macroscale, although in the macroscale, the total biomass concentration is less affected by these heterogeneities. 1Department of Earth Sciences–Geochemistry, Utrecht University, Utrecht, Netherlands. Mr. Konstantin Stolpovsky is corresponding author. E-mail: email@example.com 2Department of Environmental Microbiology, UFZ–Helmholtz Centre for Environmental Research, Leipzig, Germany. Received August 5, 2011. Accepted for publication November 8, 2011. Financial Disclosures/Conflicts of Interest: This study was supported by the Helmholtz Association through grant VG-NG-338 (GReaT MoDE) and via the program topic “CITE-Chemicals in the Environment.” Further support was provided by the European Union Marie Curie Host Early Stage Training (EST) through grant MC-EST 20984 (RAISEBIO). © 2012 Lippincott Williams & Wilkins, Inc.