Dependence ofPenicillium chrysogenum growth, morphology, vacuolation, and productivity in fed-batch fermentations on impeller type and agitation intensity

Abstract

The influence of the agitation conditions on the growth, morphology, vacuolation, and productivity of Penicillium chrysogenum has been examined in 6 L fed‐batch fermentations. A standard Rushton turbine, a four‐bladed paddle, and a six‐bladed pitched blade impeller were compared. Power inputs per unit volume of liquid, P/VL, ranged from 0.35 to 7.4 kW/m3. The same fermentation protocol was used in each fermentation, including holding the dissolved oxygen concentration above 40% air saturation by gas blending. The mean projected area (for all dispersed types, including clumps) and the clump roughness were used to characterize the morphology. Consideration of clumps was vital as these were the predominant morphological form. For a given impeller, the batch‐phase specific growth rates and the overall biomass concentrations increased with agitation intensity. Higher fragmentation at higher speeds was assumed to have promoted growth through increased formation of new growing tips. The mean projected area increased during the rapid growth phase followed by a sharp decrease to a relatively constant value dependent on the agitation conditions. The higher the speed, the lower the projected area for a given impeller type. The proportion by volume of hyphal vacuoles and empty regions decreased with speed, possibly due to fragmentation in the vacuolated regions. The specific penicillin production rate was generally higher with lower impeller speed for a given impeller type. The highest value of penicillin production as well as its rate was obtained using the Rushton turbine impeller at the lowest speed. At given P/VL, changes in morphology, specific growth rate, and specific penicillin production rate depended on impeller geometry. The morphological data could be correlated with either tip speed or the “energy dissipation/circulation function,” but a reasonable correlation of the specific growth rate and specific production rate was only possible with the latter. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:762–775, 1998.

Autophagy Deficiency Promotes β-Lactam Production in Penicillium chrysogenum

“…In P. chrysogenum, the biosynthetic pathway of ␤-lactam antibiotics is compartmentalized and is suggested to take place in mature, vacuolated subapical hyphal compartments (10,27). Extensive autophagy-related degradation of cytosolic components and peroxisomes in vacuolated, late hyphal elements was strains.…”

Fungal morphology and fragmentation behavior in a fed-batchAspergillus oryzae fermentation at the production scale

“…1, Table II) has been found to correlate better with morphological and fragmentation data than power (P) per unit volume (V L ) (Justen et al, 1996(Justen et al, , 1998bAmanullah et al, 1999), impeller power is reported in terms of EDCF. For each sample time, EDCF was determined for each of the three impellers in the particular tank.…”

“…(3) (Smith et al, 1990;Justen et al, 1998b) N Fl = ͩ 0.91N P W D i ͪ 1/2 (4a) (Platzer and Noll, 1983;Justen et al, 1996) N Fl, g = N Fl ͩ N P, g N P ͪ (4b) (Justen et al, 1998b) N Ae = Q air ND i, bottom 3 (5) (Bailey and Ollis, 1986;Atkinson and Mavituna, 1991) P, gassed impeller power; k , geometric constant; D i , impeller diameter; W, impeller blade height; V L , volume of liquid; N Fl , ungassed flow number; N Fl,g , gassed flow number; N P , ungassed power number; N P, g , gassed power number; Q air , volumetric air flow rate; D i ,bottom , diameter of bottom impeller. To calculate EDCF for each impeller, total gassed power must be appropriately distributed to each of the three impellers in the fermentor.…”

Excess turbulence as a cause of turbohypobiosis in cultivation of microorganisms

“…In conditions where the intensity of local turbulence is high but insufficient for the mechanical disruption of the cultivated cells, changes in the cell morphology were often observed [2,56,62,[66][67][68][69][70][71][72][73][74][75][76]. Simultaneously with morphological adjustment, the physiological character, namely, the productivity of metabolite synthesis [66,67,69,72,73,76], biological activity [70,74,77] and enzyme activity [71] also changed.…”

“…Simultaneously with morphological adjustment, the physiological character, namely, the productivity of metabolite synthesis [66,67,69,72,73,76], biological activity [70,74,77] and enzyme activity [71] also changed. Hence, these morphological changes may be regarded to be not a simple result of the mechanical deformation of cells, but a reaction to the changes in cultivation conditions.…”