Novel insights in transport mechanisms and kinetics of phenylacetic acid and penicillin-G in Penicillium chrysogenum

Although penicillin‐G (PenG) production by the fungus Penicillium chrysogenum is a well‐studied process, little is known about the mechanisms of transport of the precursor phenylacetic acid (PAA) and the product PenG over the cell membrane. To obtain more insight in the nature of these mechanisms, i...

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Bibliographic Details
Published in:Biotechnology progress 2012-03, Vol.28 (2), p.337-348
Main Authors: Douma, Rutger D., Deshmukh, Amit T., de Jonge, Lodewijk P., de Jong, Bouke W., Seifar, Reza M., Heijnen, Joseph J., van Gulik, Walter M.
Format: Article
Language:English
Subjects:
Biological and medical sciences
Biological Transport
Biotechnology
Cell Membrane - chemistry
Cell Membrane - metabolism
Fundamental and applied biological sciences. Psychology
Kinetics
membrane transport mechanisms
penicillin
Penicillin G - chemistry
Penicillin G - metabolism
Penicillium chrysogenum
Penicillium chrysogenum - chemistry
Penicillium chrysogenum - genetics
Penicillium chrysogenum - metabolism
Phenylacetates - chemistry
Phenylacetates - metabolism
phenylacetic acid
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Summary:Although penicillin‐G (PenG) production by the fungus Penicillium chrysogenum is a well‐studied process, little is known about the mechanisms of transport of the precursor phenylacetic acid (PAA) and the product PenG over the cell membrane. To obtain more insight in the nature of these mechanisms, in vivo stimulus response experiments were performed with PAA and PenG in chemostat cultures of P. chrysogenum at time scales of seconds to minutes. The results indicated that PAA is able to enter the cell by passive diffusion of the undissociated acid at a high rate, but is at the same time actively excreted, possibly by an ATP‐binding cassette transporter. This results in a futile cycle, dissipating a significant amount of metabolic energy, which was confirmed by increased rates of substrate and oxygen consumption, and carbon dioxide production. To estimate the kinetic properties of passive import and active export of PAA over the cell membrane, a dynamic mathematical model was constructed. With this model, a good description of the dynamic data could be obtained. Also, PenG was found to be rapidly taken up by the cells upon extracellular addition, indicating that PenG transport is reversible. The measured concentration gradient of PenG over the cell membrane corresponded well with facilitated transport. Also, for PenG transport, a dynamic model was constructed and validated with experimental data. The outcome of the model simulations was in agreement with the presence of a facilitated transport system for PenG. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2012
ISSN:8756-7938
1520-6033
DOI:10.1002/btpr.1503