Rheological characterization of media containing <i>Penicillium chrysogenum</i>

Pedersen, Annemarie Gade; Bundgaard-Nielsen, M.; Nielsen, Jens; Villadsen, John; Hassager, Ole

doi:10.1002/bit.260410121

Cited by 47 publications

(35 citation statements)

References 4 publications

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“…For design purposes it might be adequate to assume n ‫ס‬ 0.35 for any biomass levels >10 g L −1 . This agrees well with the data of Pedersen et al (1992), although it must be considered that the actual n value achieved could be strain-specific. However, because n is an exponent in the power law, changes in n will have large effects on the broth apparent viscosity, and using the average value for n in the very late fed batch stages of a fermentation is a questionable approach, when the values of n may actually be much closer to 0.2 (Fig.…”

Section: Resultssupporting

confidence: 86%

Effect of biomass concentration and mycelial morphology on fermentation broth rheology

Riley

Tucker

Paul

et al. 2000

Biotechnol. Bioeng.

114

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Section: Resultssupporting

confidence: 86%

Effect of biomass concentration and mycelial morphology on fermentation broth rheology

Riley

Tucker

Paul

et al. 2000

Biotechnol. Bioeng.

114

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“…The morphology is assumed to affect productivity in two ways. Firstly, fungal macro-and micromorphology is known to affect the rheology of the fermentation medium (Bocking et al, 1999 ;Pedersen et al, 1993), thereby having a significant impact on the mixing, mass transfer and aeration within the bioreactor. This in turn may have an impact on protein production, which requires efficient mixing and aeration of the culture.…”

Section: Introductionmentioning

confidence: 99%

Morphological characterization of Aspergillus nidulans: growth, septation and fragmentation

2001

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The influence of the sepA gene on the growth of Aspergillus nidulans has been investigated by characterizing and comparing the parental strain A28 (pabaA6 biA1) with the sepA null mutant (sepA4∆Bm). The sepA gene is known to affect the septation process in A. nidulans, therefore the sepA4∆Bm strain does not produce any septa during the first hours of growth. During batch cultivations sepA4∆Bm shows an abrupt decrease in specific growth rate and more pronounced fragmentation (in response to elevated stirrer speed) than the parental strain. Higher specific fragmentation rates (q frag ) were obtained for the sepA4∆Bm strain. The physiological reasons for the differences have been investigated by employing fluorescent stains. Computerized image analysis revealed that the more pronounced fragmentation in the mutant was due to the lower number and irregular spacing of septa (visualized by calcofluor white staining), which resulted in a weaker hyphal structure that is more vulnerable to shear stress and fragmentation than the parental strain. This led to a loss of active biomass (determined by Mag fura staining) from the hyphae of the mutant, which had failed to compartmentalize by formation of septa, in turn resulting in decreased specific growth rates for the culture.

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“…Using the power law model coef®-cients obtained above (Table 3), the apparent viscosity was estimated for various cultivation times (Table 4). These estimations were compared qualitatively with those obtained using the method of Metzner [1,23,24,33], based on the P g /P 0 versus N A and N P versus N Re data from glycerol at an impeller speed of 4.6 s A1 (Table 4).…”

Section: Viscosity Measurements and Estimation Of Apparent Viscositymentioning

confidence: 99%

Influence of impeller type on mass transfer in fermentation vessels

Junker

Stanik

Barna

et al. 1998

Bioprocess Engineering

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Radial¯ow Rushton impellers were compared qualitatively with axial¯ow hydrofoil impellers (Max¯o T and A315) at the pilot scale. Six types of impellers were compared for qualitative differences in mass transfer. Measurements were conducted using three model systems: water, glycerol and Melojel (soluble starch). Power measurements were obtained using watt transducers, which although limited in accuracy and prone to interferences, were able to provide useful qualitative monitoring results. While there was little effect of impeller type on mass transfer as measured by the rapid pressure increase technique, signi®cant qualitative differences were observed using the rapid temperature increase technique speci®cally for the Melojel and glycerol model systems. The Miller correlation, relating gassed-to-ungassed power, was used effectively to qualitatively evaluate the power drop upon gassing for both the model systems and a Streptomyces fermentation for the various impeller types.A high oxygen demand Streptomcyes fermentation then was conducted in fermenters possessing each type of impeller. Performance was not adequate with the A315 impellers pumping upwards and the small diameter Max¯o T impellers. Peak titers and pro®les of the estimated apparent broth viscosity varied depending upon the impeller type. Mass transfer rates generally declined with higher viscosities when other fermentation operating conditions where held constant. Overall, values for OUR, k L a, P g /V L and other calculated mass transfer and power input quantities for the A315 pumping upwards and undersized Max¯o T (D T /D I 2.3) impellers were at the lower end of the range obtained for the larger Max¯o T (D T /D I 1.8± 2.0) and A315 impellers pumping downwards. Rushton impellers generally behaved qualitatively similar to hydrofoil impellers based on these calculated quantities. List of symbolsa surface area per unit volume of bubbles, cm A1 g gravitational constant, m/s 2 k¯uid consistency index k L mass transfer coef®cient n power law index t m mixing time, s v b bulk velocity, m/s v s super®cial velocity of sparged air based on tank diameter, m/s A cross-sectional area of the tank, m 2 D I impeller diameter (tip to tip), m D T fermenter vessel diameter, m D oi diffusivity of oxygen in water (w), glycerol (g) andMelojel (m), cm 2 /s N impeller speed, s A1 N A aeration or¯ow number, Q/ND 3 I N Fr Froude number, N 2 /D I g N m Mixing number, 1/t m N N P Newton or power number, P 0 /(qN 3 D 5 I ) N Q generalized pumping number, Q P /ND 3 I N Re Reynold's number for impeller, ND 2 I q/l N Sc Schmidt number, l/qD oi P 0 ungassed power draw, kW P g gassed power draw, kW Q volumetric gas¯owrate, m 3 /s Q P volumetric pumping rate, v b A, m 3 /s V L ungassed liquid volume of tank, m 3 q liquid density, g/cm 3 l viscosity, mPa á s l a apparent viscosity, mPa á s c T average shear rate in stirred tank, s A1 r surface tension, dynes/cm 1 Introduction For aerobic fermentations, oxygen management is about 15±20% of all operating costs. Consequently, a modest impr...

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Rheological characterization of media containing Penicillium chrysogenum

Cited by 47 publications

References 4 publications

Effect of biomass concentration and mycelial morphology on fermentation broth rheology

Effect of biomass concentration and mycelial morphology on fermentation broth rheology

Morphological characterization of Aspergillus nidulans: growth, septation and fragmentation

Influence of impeller type on mass transfer in fermentation vessels

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