Insights into Biomass Growth and Permeability Reduction in Soils – microfluidic application

Abstract

The interplay between biomass growth and its impact on the porosity and permeability of porous media is influenced by the bacterial community, the pore structure, and the prevailing conditions such as flow rate. This study employs a microfluidic device with realistic pore structures, to investigate the growth of a naturally occurring soil bacterium, Pseudomonas sp. RA12, known for biofilm production, under no-flow conditions during incubation. By saturating the microfluidic device and inoculating it with a Pseudomonas sp. RA12 culture at an OD600 of 0.365, along with a nutrient solution (TSB), biomass was successfully cultivated within the porous medium. Permeability measurements, biofilm staining, and confocal laser scanning microscopy were utilized to conduct a comprehensive experiment assessing the permeability reduction over time due to Pseudomonas sp. RA12 growth. After 143.8 hours at the optimal growth temperature of 28°C, the microfluidic's permeability decreased by 70.2%. Confocal microscopy revealed the biofilm structures at 400x magnification and their distribution within the microfluidic environment. Confocal imaging reveals the dynamic stages of Pseudomonas sp. RA12 biofilm formation in a microfluidic device, emphasizing the concentration of biofilm development in pore throats and the prevalence of multi-line structures over time. The results, following computational analysis of the images, have the potential to enhance modelling experiments. This study significantly advances our understanding of biomass growth dynamics in porous media.