Growth and product formation ofAspergillus oryzae during submerged cultivations: Verification of a morphologically structured model using fluorescent probes

Agger, Teit; Spohr, Anders Bendsen; Carlsen, Morten; Nielsen, Jens

doi:10.1002/(sici)1097-0290(19980205)57:3<321::aid-bit9>3.0.co;2-j

Cited by 66 publications

(44 citation statements)

References 19 publications

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“…Autolysis is observed at low dilution rates in glucose-limited chemostat cultures of A. nidulans (Bainbridge et al, 1971). In addition, Agger et al (1998) showed that the proportion of active biomass (containing organelles) in chemostat cultures of A. oryzae decreases with decreasing dilution rates. Thus the reduction of the maximum specific glucose uptake rate (v max ) may be a general response to starvation at low dilution rates, caused by a general reduction of metabolic capacities and/or an increasing amount of non-active biomass.…”

Section: High-affinity Glucose Uptakementioning

confidence: 99%

Glucose uptake and growth of glucose-limited chemostat cultures of Aspergillus niger and a disruptant lacking MstA, a high-affinity glucose transporter

et al. 2007

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This is a study of high-affinity glucose uptake in Aspergillus niger and the effect of disruption of a high-affinity monosaccharide-transporter gene, mstA. The substrate saturation constant (K s ) of a reference strain was about 15 mM in glucose-limited chemostat culture. Disruption of mstA resulted in a two-to fivefold reduction in affinity for glucose and led to expression of a low-affinity glucose transport gene, mstC, at high dilution rate. The effect of mstA disruption was more subtle at low and intermediate dilution rates, pointing to some degree of functional redundancy in the high-affinity uptake system of A. niger. The mstA disruptant and a reference strain were cultivated in glucose-limited chemostat cultures at low, intermediate and high dilution rate (D50.07 h "1 , 0.14 h "1 and 0.20 h "1 ). Mycelium harvested from steady-state cultures was subjected to glucose uptake assays, and analysed for expression of mstA and two other transporter genes, mstC and mstF. The capacity for glucose uptake (v max ) of both strains was significantly reduced at low dilution rate. The glucose uptake assays revealed complex uptake kinetics. This impeded accurate determination of maximum specific uptake rates (v max ) and apparent affinity constants (K app m ) at intermediate and high dilution rate. Two high-affinity glucose transporter genes, mstA and mstF, were expressed at all three dilution rates in chemostat cultures, in contrast to batch culture, where only mstC was expressed. Expression patterns of the three transporter genes suggested differential regulation and functionality of their products.

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Section: High-affinity Glucose Uptakementioning

confidence: 99%

Glucose uptake and growth of glucose-limited chemostat cultures of Aspergillus niger and a disruptant lacking MstA, a high-affinity glucose transporter

et al. 2007

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“…The morphologically structured model proposed by [6] is based on the division of the biomass into three different compartments:…”

Section: Morphology and Rate Expressionsmentioning

confidence: 99%

“…The parameter a t is described as a function of µ (see [6,10] for details concerning the morphological model). The kinetic expressions and the model parameters are presented in Appendix A.…”

Section: Morphology and Rate Expressionsmentioning

confidence: 99%

“…The expression used in [6] describes the substrate inhibition by an exponential decrease in the specific production rate of the enzyme when the substrate concentration exceeds a certain threshold value. In this study, the expression of the specific rate of enzyme production is modified by using a Haldane expression to describe the substrate inhibition.…”

Section: Morphology and Rate Expressionsmentioning

confidence: 99%

“…A first-principles model of the filamentous fungal (α-amylase producing strain of Aspergillus oryzae) fermentation process is proposed in [6], while a data-driven model is described in [7]. Here, the former is utilized.…”

Section: Introductionmentioning

confidence: 99%

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Oxygen control for an industrial pilot-scale fed-batch filamentous fungal fermentation

Bodizs

Titica

Faria

et al. 2007

Journal of Process Control

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Industrial filamentous fungal fermentations are typically operated in fed-batch mode. Oxygen control represents an important operational challenge due to the varying biomass concentration. In this study, oxygen control is implemented by manipulating the substrate feed rate, i.e. the rate of oxygen consumption. It turns out that the setpoint for dissolved oxygen represents a trade-off since a low dissolved oxygen value favors productivity but can also induce oxygen limitation. This paper addresses the regulation of dissolved oxygen using a cascade control scheme that incorporates auxiliary measurements to improve the control performance. The computation of an appropriate setpoint profile for dissolved oxygen is solved via process optimization. For that purpose, an existing morphologically structured model is extended to include the effects of both low levels of oxygen on growth and medium rheological properties on oxygen transfer. Experimental results obtained at the industrial pilot-scale level confirm the efficiency of the proposed control strategy but also illustrate the shortcomings of the process model at hand for optimizing the dissolved oxygen setpoints.

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Genetically structured modeling of protein production in filamentous fungi

Agger

Nielsen

1999

Biotechnol. Bioeng.

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Growth and product formation ofAspergillus oryzae during submerged cultivations: Verification of a morphologically structured model using fluorescent probes

Cited by 66 publications

References 19 publications

Glucose uptake and growth of glucose-limited chemostat cultures of Aspergillus niger and a disruptant lacking MstA, a high-affinity glucose transporter

Glucose uptake and growth of glucose-limited chemostat cultures of Aspergillus niger and a disruptant lacking MstA, a high-affinity glucose transporter

Oxygen control for an industrial pilot-scale fed-batch filamentous fungal fermentation

Genetically structured modeling of protein production in filamentous fungi

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