Hyphal growth and fragmentation of Penicillium chrysogenum in submerged cultures

Abstract

A previously derived population model describing the average properties of hyphal elements in submerged cultures of filamentous fungi was revised, and a term for the influence fo spore germination on the average total hyphal length was added. The model was derived from a general balance for the distribution function for the hyphal elements. Based on experimental data and the derived model, simple kinetic expressions for spore germination, tip extension, branching, and hyphal break-up were set up. It is concluded that spore germination can be quantified by three parameters: (1) the time at which spore germination is initiated, (2) the time at which spore germination terminates, and (3) the fraction of viable spores in a spore suspension. The frequency of spore germination can be described with the B-distribution. For growth kinetics it is concluded that the branching frequency is closely correlated with the total hyphal length and that the average tip-extension rate can be described with saturation kinetics with respect to the hyphal length. Finally, the rate of fragmentation is linearly related to the energy input to the bioreactor, and related to the effective hyphal length.

Image analysis of the morphology of filamentous micro-organisms

“…In addition, the fullness and size of the hairy region of the pellet could be quantified, in a way similar to clump characterization for the dispersed form. Nielsen et al (1995) developed yet another semi-automatic image analysis method to study pellets, and demonstrated a relationship between the balance of pelleted and freely dispersed forms and penicillin production from P. chrysogenum.…”

“…It has been mentioned that Nielsen et al (1995) developed a method to characterize all of the forms they observed in P. chrysogenum fermentations. It should be noted that Justen et al (1996) used projected area to describe of the dispersed forms in their agitation trials.…”

Morphological characterization of Aspergillus nidulans: growth, septation and fragmentation

“…(1) (Nielsen & Krabben, 1995) (where k frag (z) is a rate constant ( µm − " h − "). When q frag is given by (1) a balance for the mean total hyphal length l t,av can be expressed as (Nielsen & Krabben, 1995) where n av is the mean number of actively growing tips and q tip (l t,av , z) is the mean tip-extension rate in the hyphal elements (m tip − " h − ").…”

Autolysis and aging of Penicillium chrysogenum cultures under carbon starvation: Chitinase production and antifungal effect of allosamidin.

“…

IntroductionThe autolysis taking place in submerged carbon-depleted cultures of Penicillium chrysogenum is influenced by numerous intrinsic (vacuolation, age-related hydrolase production, aging) and extrinsic (power input, shearing forces, nutrient and O 2 limitations, penicillin side-chain precursors) factors (Harvey et al, 1998;McIntyre et al, 1999McIntyre et al, , 2000Nielsen and Krabben, 1995;Paul et al, 1994;Paul and Thomas, 1996;Pócsi et al, 2000; Pusztahelyi et al, 1997a, b;White et al, 1999). In some aspects, the autolysis of P. chrysogenum is reminiscent of the apoptosis of higher eucaryotes under these conditions, e.g., it is an en- In carbon-depleted cultures of Penicillium chrysogenum, age-related chitinases were shown to play a crucial role in both autolysis and fragmentation as indicated by in vivo enzyme inhibition experiments using allosamidin.

…”