Bacterial chemotaxis toward a NAPL source within a pore‐scale microfluidic chamber

Abstract

Chemotaxis toward chemical pollutants provides a mechanism for bacteria to migrate to locations of high contamination, which may improve the effectiveness of bioremediation. A microfluidic device was designed to mimic the dissolution of an organic-phase contaminant from a single pore into a larger macropore representing a preferred pathway for microorganisms that are carried along by groundwater flow. The glass windows of the microfluidic device allowed direct image analysis of bacterial distributions within the vicinity of the organic contaminant. Concentrations of chemotactic bacteria P. putida F1 near the organic/aqueous interface were 25% greater than those of a nonchemotactic mutant in the vicinity of toluene for a fluid velocity of 0.5 m/d. For E. coli responding to phenol, the bacterial concentrations were 60% greater than the controls, also at a velocity of 0.5 m/d. Velocities in the macropore were varied over a range from 0.5 to 10 m/d, the lower end of which is typical of groundwater velocities. The accumulation of chemotactic bacteria near the NAPL chemoattractant source decreased as the fluid velocity increased. Good agreement between computer-based simulations, generated using reasonable values of the model parameters, and the experimental data for P. putida strains confirmed the contribution due to chemotaxis. The experimental data for E. coli required a larger chemotactic sensitivity coefficient than that for P. putida, which was consistent with parameter values reported in the literature.

Application of Microfluidics for the Study of Bacterial Chemotaxis to NAPL in Porous Media

“…shows that the distribution of both chemotactic and nonchemotactic bacteria followed the trend predicted by the mathematical models with the parameters fitted from the previous chapter, which are listed in Table 6 consistent with what were reported from previous studies in the single-pore device (Wang et al, 2012). However, the previous study only measured chemotaxis near one single pore slit; this study successfully captured similar results in a porous structure, designed to mimic a more complex groundwater system with contaminant sources.…”

Chemotaxis migration and morphogenesis of living colonies

“…It varies linearly with the bacterium and the chemoattractant densities. In other experimental geometry, the model for regular fronts can be adapted without difficulty [36].…”

Microfluidic tools toward industrial biotechnology

“…These researches involving motility mechanisms have been applied in different areas, including biorremediations and quantification of waterborne pathogens in microfluidics. Wang et al (2015) employed a similar microfluidic device model, which was used before for mammalian cells by Atencia et al (2012), to investigate the migration of Pseudomonas putida bacteria populations in the presence of toluene, an industrial chemical pollutants, which the cells are able to degrade it.…”

“…These and other bacterial motility mechanisms that were evaluated in microfluidic systems can be found on review of Son et al (2015). 9 These researches involving motility mechanisms have been applied in different areas, including biorremediations 132,134 and quantification of waterborne pathogens 135 69 to investigate the migration of Pseudomonas putida bacteria populations in the presence of toluene, an industrial chemical pollutants, which the cells are able to degrade it. Furthermore, it was possible to determinate parameters linked to chemotaxis processes, leading to a better understanding of these cells dynamics.…”