Abstract
Microhabitat conditions determine the magnitude and speed of microbial processes but have been challenging to investigate. In this study we used microfluidic devices to determine the effect of the spatial distortion of a pore space on fungal and bacterial growth, interactions, and substrate degradation. The devices contained channels differing in bending angles and order. Sharper angles reduced fungal and bacterial biomass, especially when angles were repeated in the same direction. Substrate degradation was only decreased by sharper angles when fungi and bacteria were grown together. Investigation at the cellular scale suggests that this was caused by fungal habitat modification, since hyphae branched in sharp and repeated turns, blocking the dispersal of bacteria and the substrate. Our results demonstrate how the geometry of microstructures can influence microbial activity. This can be transferable to soil pore spaces, where spatial occlusion and microbial feedback on microstructures is thought to explain organic matter stabilization.
Highlights
Microhabitat conditions determine the magnitude and speed of microbial processes but have been challenging to investigate
In the present study we have developed a microfluidic approach to explore the effect of a simulated pore space, consisting of differently angled channels, on fungal and bacterial biomass distribution and organic matter degradation
While all channels were colonized over their whole length, there were significant differences in the amount of bacterial biomass depending on the angle and order of their turns (Fig. 2a)
Summary
Microhabitat conditions determine the magnitude and speed of microbial processes but have been challenging to investigate. X-ray tomography studies have revealed correlations between pore size and SOM losses, feedback of SOM decay on the porous space, and an influence of pore heterogeneity, and their connection to the atmosphere as determinants of SOM fate[16,17,18,19,20] Studies using these techniques have, limitations such as the lack of a controlled and manipulatable environment, the lack of real-time measurement of processes in the inner space, disturbance of natural conditions during sample preparation, subjectivity when thresholding greyscale images, and a current resolution limit of a few tens of micrometers which does not allow the study of smaller micropores[21]
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