Influence of engineering variables upon the morphology of filamentous molds

Abstract

SummaryA model has been described for the influence of growth rate and shear stresses in the fermentor upon the morphology of filamentous molds. The main concept of this model is the dynamic equilibrium between growth and breakup of the hyphae. The latter has been approached according to well-known engineering theories for dispersion of physical systems. Experiments to verify the model with a strain of Penicilliurn chrysogenurn in batch and continuous culture revealed that the length of the mycelial particles increased with increasing growth rate and decreased with increasing power input per unit mass in the fermentor. Although this was qualitatively in agreement with the presented model, quantitatively the model had to be rejected. Variation of the tensile strength of the hyphae with age and culturing conditions could have been one of the causes of disagreement. Oxygen tension, varied independently from stirrer speed, in the range of 12-300 mm Hg was shown to have no influence upon the morphology. With respect to the question of possibly using high-energy inputs in industrial mold fermentation in order to decrease hyphal length and suspension viscosity, it was concluded that this is of little practical value. A substantial decrease in hyphal length requires an enormous increase in energy input.

Effect of transport phenomena of Cladosporium cladosporioides on decolorization and chemical oxygen demand of distillery spent wash

“…It was decided in a report that the shape of the pellet and agglomeration mainly depend on the aeration and agitation in bioreactor (Smith et al 1990;Van Suijdam and Metz 1981). Pellet formation, roughness factor, and hyphal measurements were the predominant factors, affecting the decolorization and degradation of the distillery spent wash.…”

Characterization of Fungal Morphology using Digital Image Analysis Techniques

“…The method was more accurate and faster than the digitizing tables used by Metz et al [6] and van Suijdam and Metz [7] in the early 1980s although considerable manual intervention was still required, e.g. binary images were manually edited.…”

“…Great progress has been made in this area since the 1970s when investigations relied upon manual measurements performed under a microscope or on photographs were reported. Progress was made with the use of simple digitizing tables in the works of Metz et al [6] and van Suijdam and Metz [7]. Progressively, with the availability of personal computers and digital video cameras, image analysis systems were developed.…”

Mass Transfer in Bioreactors

“…N Sc is equal to νD L -1 and approximately 3991 with D L the molecular diffusion coefficient of dissolved O 2 in H 2 O (m 2 h -1 ). ∈ in the impeller jet stream can be given as a function of the distance from the impeller shaft (r is ), the stirrer speed (N), and the stirrer diameter (D R ) (Van Suijdam and 1981, Metz):…”