Kinetic parameter estimation in N. europaea biofilms using a 2-D reactive transport model

Area of Science:

• Microbial Ecology
• Environmental Microbiology
• Biogeochemical Cycles

Background:

• Biofilms are microbial communities with distinct properties compared to planktonic cells.
• Ammonia oxidation is a key step in nitrification, essential for nitrogen cycling.
• Nitrosomonas europaea is a significant ammonia-oxidizing bacterium.

Purpose of the Study:

• To investigate ammonia oxidation kinetics in Nitrosomonas europaea biofilms.
• To compare biofilm kinetic parameters with those of suspended cells.
• To model the influence of transport and chemical processes on ammonia oxidation within biofilms.

Main Methods:

• Cultivation of Nitrosomonas europaea biofilms.
• Microsensor measurements of dissolved oxygen (DO) and pH.
• Two-dimensional (2-D) reactive transport modeling.

Main Results:

• Modeled DO and pH profiles showed good agreement with experimental data.
• The half-saturation coefficient (Ksn) for ammonia (NH3) in biofilms was similar to suspended cells.
• Deviations occurred at low NH3 concentrations, and pH gradients were predicted under limited buffering.

Conclusions:

• Biofilm ammonia oxidation kinetics are comparable to suspended cells under certain conditions.
• Reactive transport modeling is essential for understanding complex biofilm processes.
• Transport and chemical factors significantly influence ammonia oxidation in N. europaea biofilms.