Bacterial Dispersers along Preferential Flow Paths of a Clay Till Depth Profile

Area of Science:

• Soil Microbiology
• Environmental Science
• Biogeochemistry

Background:

• Bacterial dispersal is crucial for soil ecosystem function and survival.
• Understanding dispersal from heterogeneous soil compartments is limited.
• Soil moisture and connectivity influence bacterial movement.

Purpose of the Study:

• To assess bacterial community dispersal from various soil compartments in a fractured clay till profile.
• To investigate the role of hydration conditions on bacterial dispersal.
• To identify dominant bacterial taxa involved in dispersal.

Main Methods:

• Utilized an expanded porous surface model (PSM) for controlled dispersal experiments.
• Analyzed bacterial communities using 16S rRNA gene amplicon sequencing.
• Assessed dispersal across a soil depth profile (350 cm) including plow layer, preferential flow paths, and matrix sediments.

Main Results:

• All tested communities exhibited active dispersal, even at low hydration levels (-3.1 kPa).
• Plow layer communities dispersed at matric potentials as low as -8.4 kPa.
• Dispersing communities were less diverse than total communities, often dominated by *Pseudomonas*, *Rahnella*, or *Pantoea*.

Conclusions:

• Active bacterial dispersal is common across diverse soil compartments and depths.
• Soil profile heterogeneity and connectivity are critical factors for dispersal.
• Dispersal plays a significant role in colonizing preferential flow paths in fractured clay till.