The role of water in solid-state fermentation

Solute diffusion as well as cell absorption occurs in aqueous medium. Thermodynamics and kinetic parameters relative to water motion in solid media are successively examined with regard to their consequence on the solid-state fermentation (SSF). Specific attention is focused on fungal physiology: . at microscopic level through the influence of cell water flux on the maintenance of a constant cell turgor pressure, through the constant branching orientation and hyphal growth rate; . at macroscopic level through the influence of the hydration on the maintenance of a radial growth rate, on the evolution of germination, sporulation and metabolic activity of a fungal colony. Interactions between water status, oxygen supply and heat removing from SSF are finally pointed out. (C) 2002 Elsevier Science B.V. All rights reserved.