Universal law for diffusive mass transport through mycelial networks.

Area of Science:

• Biotechnology
• Circular Economy
• Bioprocess Engineering
• Mycology

Background:

• Filamentous fungi are crucial for biotechnology and the circular economy, but controlling their hyphal growth and macroscopic morphology for optimal product titers remains challenging.
• Industrial cultivations often result in fungal pellets, characterized by dense networks of branched hyphae.
• The core of these pellets experiences nutrient and oxygen depletion due to limited diffusive mass transport, negatively impacting bioprocess productivity.

Purpose of the Study:

• To demonstrate the existence of a generalized law for diffusive mass transport within filamentous fungal pellets.
• To establish a predictive model for diffusion within these pellets, applicable to nutrients, oxygen, and secreted metabolites.
• To advance the rational design of fungal pellet morphologies at both genetic and process engineering levels.

Main Methods:

• Conducted diffusion computations using three-dimensional X-ray microtomography on 66 fungal pellets from four industrially relevant filamentous fungi.
• Utilized 3125 Monte Carlo simulations of pellets to complement experimental data.
• Analyzed the relationship between the diffusion hindrance factor and the solid hyphal fraction.

Main Results:

• Identified a generalized scaling law for diffusive mass transport in filamentous fungal pellets.
• Demonstrated that the diffusion hindrance factor scales with the solid hyphal fraction.
• Validated the law across diverse fungal species and pellet structures.

Conclusions:

• The discovered scaling law provides a predictable framework for mass transport within fungal pellets.
• This finding will enable the optimization of fungal pellet morphology for enhanced bioprocess efficiency and productivity.
• The research facilitates the rational engineering of fungal cell factories for improved biotechnology and circular economy applications.