Modeling the Growth of Filamentous Fungi at the Particle Scale in Solid-State Fermentation Systems

Abstract

Solid-state fermentation (SSF) with filamentous fungi is a promising technique for the production of a range of biotechnological products and has the potential to play an important role in future biorefineries. The performance of such processes is intimately linked with the mycelial mode of growth of these fungi: Not only is the production of extracellular enzymes related to morphological characteristics, but also the mycelium can affect bed properties and, consequently, the efficiency of heat and mass transfer within the bed. A mathematical model that describes the development of the fungal mycelium in SSF systems at the particle scale would be a useful tool for investigating these phenomena, but, as yet, a sufficiently complete model has not been proposed. This review presents the biological and mass transfer phenomena that should be included in such a model and then evaluates how these phenomena have been modeled previously in the SSF and related literature. We conclude that a discrete lattice-based model that uses differential equations to describe the mass balances of the components within the system would be most appropriate and that mathematical expressions for describing the individual phenomena are available in the literature. It remains for these phenomena to be integrated into a complete model describing the development of fungal mycelia in SSF systems.

Functionality of Surface Mycelium Interfaces in Wood Bonding

“…Therefore, the top and bottom surfaces reveal the properties of aerial and biofilm hyphae, respectively. The biofilm hyphae hold more moisture and are shown as densely packed structures, whereas the aerial hyphae are directly in contact with the gas phase and hold air in their porous structure . At the initial stages of white-rot fungal metabolism, enzymes are first released by the biofilm hyphae to the substrate through the diffusion medium, which is water.…”

“…Multiple approaches could be followed to further improve its bonding strength and water resistance. For the wood pretreatment purpose, mixing the growing system continuously may stop the development of aerial hyphae, only biofilm hyphae would exist at the interfaces, and the adhesion could be improved. For the stand-alone adhesive purposes, surface mycelium could be produced at a large-scale in bioreactors with more control of the nutrient supply and air flow .…”

“…According to Sugai-Gueŕios et al in 2015, there are three basic types of hyphae in the solid-state fermentation system: the aerial hyphae, the biofilm hyphae, and the penetrative hyphae, as shown in the sketch in Figure 7I. 20 As there were no hyphae visible on the wood surface after removing the surface mycelium layer (Figure 4A), the bottom mycelium layer must include the biofilm hyphae. Therefore, the top and bottom surfaces reveal the properties of aerial and biofilm hyphae, respectively.…”

“…The mycelium body, which works as an entanglement in foam-like mycelium composites, may also contribute to the bonding. During the colonization of fungi on lignocellulosic substrates, hyphae first develop and elongate on the substrate surface from originally loaded mycelial fragments. , This layer of aerial hyphae or surface mycelium significantly changes the surface morphology and surface energy of the substrate. − At the same time, the outer layer of fungal hyphae contains proteins and glycoproteins, , which are typical adhesive candidates and may act as adhesive in the composite system …”

Enhanced hypocrellin production of Shiraia sp. SUPER-H168 by overexpression of alpha-amylase gene

“…bambusicola . Fig 1 shows phenomena involved in the growth of biofilm, penetrative, and aerial hyphae [ 22 ]. In cell, glucose is converted to pyruvate through glycolysis, and then pyruvate is converted to acetyl-CoA and malonyl-CoA.…”