Biofilm In Microbiology

What Is Biofilm?

A biofilm is a structured community of microorganisms attached to a surface and embedded in a self-produced matrix of polymers, proteins, and water. Instead of behaving like isolated free-swimming cells, microbes in a biofilm operate as a layered collective with shared transport pathways and chemical gradients. Diffusion inside a biofilm is often described by J = -D dC/dx, showing how nutrients, oxygen, or metabolites move through the matrix by concentration differences.

In real systems, biofilms form on metals, membranes, rocks, tissues, and electrodes, and their thickness strongly affects mass transport and reaction rates. On bioelectrochemical reactor surfaces, a mature biofilm can increase microbial loading while also creating internal gradients in pH and substrate availability. Used in devices include microbial fuel cells, membrane bioreactors, medical catheters, and corrosion monitoring systems.

The concept matters because biofilms can either improve performance or create persistent operational problems. They protect microorganisms from shear stress and chemical attack, but they can also reduce flow, foul membranes, corrode infrastructure, or limit how quickly reactants reach active cells. Their behavior is therefore central to both environmental engineering and industrial process design.

Scientists characterize biofilms with microscopy, thickness measurements, impedance, and shear-removal tests to understand structure and function together. Those measurements show whether a surface community is thin and reactive, dense but transport-limited, or unstable under changing operating conditions.

Example:
A conductive anode covered by a mature Geobacter biofilm can support current generation from wastewater while inner layers rely on transport through the surrounding matrix.

Related Terms:

• Exoelectrogens
• Microbial Nanowires
• Power Density