Diffusion of lactose in acidogenic biofilms

Area of Science:

• Microbiology
• Biochemical Engineering
• Mass Transport Phenomena

Background:

• Acidogenic biofilms play a crucial role in various biotechnological processes.
• Understanding nutrient diffusion within biofilms is essential for optimizing their performance.
• Lactose is a key substrate utilized by many acidogenic bacteria.

Purpose of the Study:

• To measure the effective diffusivity of lactose in active acidogenic biofilms.
• To elucidate the factors contributing to reduced lactose diffusion within biofilms.
• To provide a model parameter for reaction-diffusion equations describing biofilm processes.

Main Methods:

• Utilized a specially designed diffusion cell for in situ measurements.
• Maintained steady-state conditions to measure lactose concentrations.
• Employed a reaction-diffusion equation to model lactose distribution.

Main Results:

• The effective diffusivity of lactose in active acidogenic biofilms was determined to be approximately 65% of its diffusivity in free solutions.
• Biofilms exhibited a void volume of about 66%, composed of transport channels.
• The reduction in lactose diffusivity was primarily attributed to the solid biomass fraction of the biofilm.

Conclusions:

• The solid biomass fraction significantly impedes lactose diffusion more than channel tortuosity.
• These findings are crucial for modeling and enhancing microbial processes involving biofilms.
• Accurate diffusivity values are vital for predicting substrate availability and microbial activity within biofilms.