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Appl. Environ. Microbiol., Jul 1995, 2589-2595, Vol 61, No. 7
DJ Hillenga, HJM Versantvoort, S van der Molen, AJM Driessen and WN Konings
Penicillium chrysogenum utilizes phenylacetic acid as a side chain
precursor in penicillin G biosynthesis. During industrial production of
penicillin G, phenylacetic acid is fed in small amounts to the medium to
avoid toxic side effects. Phenylacetic acid is taken up from the medium and
intracellularly coupled to 6-aminopenicillanic acid. To enter the fungal
cell, phenylacetic acid has to pass the plasma membrane. The process via
which phenylacetic acid crosses the plasma membrane was studied in mycelia
and liposomes. Uptake of phenylacetic acid by mycelium was nonsaturable,
and the initial velocity increased logarithmically with decreasing external
pH. Studies with liposomes demonstrated a rapid passive flux of the
protonated species through liposomal membranes. These results indicate that
phenylacetic acid passes the plasma membrane via passive diffusion of the
protonated species. The rate of phenylacetic acid uptake at an external
concentration of 3 mM is at least 200-fold higher than the penicillin
production rate in the Panlabs P2 strain. In this strain, uptake of
phenylacetic acid is not the rate-limiting step in penicillin G
biosynthesis.
Copyright © 1995, American Society for Microbiology
Penicillium chrysogenum Takes up the Penicillin G Precursor Phenylacetic Acid by Passive Diffusion
Department of Microbiology, Groningen Biomolecular Science and Biotechnological Institute, University of Groningen, 9751 NN Haren, The Netherlands
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