Soil heterogeneity helps bacteria find nutrients
Microorganisms regulate key processes in soils and aquifers, including nutrient cycling, carbon turnover and contaminant degradation. Many bacteria use chemotaxis, the ability to sense and swim toward chemical signals, to locate nutrient-rich hotspots. However, natural subsurface environments are highly heterogeneous, containing complex pore networks that create strong variations in fluid flow…
Researchers from ETH Zurich and Eawag have developed a microfluidic platform to study how soil bacteria find nutrients in complex pore networks. The study, published in the Proceedings of the National Academy of Sciences, reveals that physical heterogeneity in natural subsurface environments enhances bacterial motility and chemotaxis, the ability to sense and move towards chemical signals.
By creating controlled nutrient hotspots within the platform, the team observed that complex porous structures generate low-velocity regions where bacteria can linger and more effectively navigate towards nutrient sources. This advantage of chemotaxis increased by approximately 1.5-fold in highly heterogeneous media compared to uniform flow environments.
The research also shows that pore-scale heterogeneity allows chemotaxis to remain advantageous across a wider range of flow velocities. These findings highlight the importance of microscale physical heterogeneity in shaping microbial behavior in the subsurface, providing new insights for understanding soil respiration, nutrient cycling, groundwater remediation, and environmental management.
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