Understanding the external surface of fungal mycelia

Overview

The way in which fungal cultures grow in liquid cultures are can have a major impact on scale up and producing material. Here, we will examine the growth of three fast-growing filamentous fungi and try understand how various growth parameters affect the morphology that will range from loose mycelia to compact pellets.

Fungal morphology is affected by inoculum (form, concentration and growth stage), media components (type and concentration of carbon, nitrogen and phosphate, trace minerals, pH, salt content), dissolved gases (dissolved oxygen and carbon dioxide), and physical factors (temperature, fermenter geometry, agitation systems, rheology, inclusion of nanoparticles and the culture modes (batch, fed-batch or continuous). It is very difficult to deduce unequivocal general relationships between process variables, product formation and fungal morphology, because a single change can affect these interrelationships - and the interactions are not fully understood.

To develop a robust scale-able process involving any filamentous organism, it is essential to have a consistent morphology that is optimal for growth rate and product synthesis. Filamentous fungi growth morphology varies from free mycelia to spherical pellets (compact or diffuse). This strongly impacts mass transfer of carbon, nutrients and oxygen. Both have advantages and disadvantages and their desirability varies according to species cultured and product synthesis. In general, a broth rich in mycelial strands has better mass transfer to the biomass, but has a high viscosity. A pellet-rich broth requires less energy to stir, but has nutrient and oxygen gradients across the pellet. Generally, the desired morphology is small compact pellets.

Ideally, we would like to understand how surface proteins and the tendency for surfaces of the fungi stick together (hydrophobicity) affect growth morphology, as this has significant application to biotechnological advancements and large-scale fermentation by filamentous fungi.

Research activities

• Submerged fermentation.
• Rheology.
• Particle characterisation.
• Surface protein characterisation.
• Surface attraction/repulsion.

Outcomes

The primary aim to understand how surface proteins, and the tendency for surfaces of the fungi stick together (hydrophobicity), affect growth morphology in industry-relevant strains.

We would like to establish if there is potential to upregulate hydrophobic surface components of these organisms such that strains that have a greater tendency to form compact pellets.

This has significant application to biotechnological advancements and large-scale fermentation by filamentous fungi. Choice of fungal strains could have relevance to pharmaceutical products, dietary protein and alternative meat products, fungal leather and dietary fatty acids and lipids.

Skills and experience

Students' skillsets and aptitudes will be assessed on a case-by-case basis.

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Keywords

• fungi
• filamentous
• protein
• submerged fermentation
• applied mycology
• biorefinery
• rheology
• biopolymer

Contact

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