Appl Environ Microbiol. 1995 Jul;61(7):2589-95. doi: 10.1128/aem.61.7.2589-2595.1995.
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.
产黄青霉利用苯乙酸作为青霉素 G 生物合成的侧链前体。在青霉素 G 的工业生产中，苯乙酸以小剂量添加到培养基中，以避免产生毒性副作用。苯乙酸从培养基中被吸收，并在细胞内与 6-氨基青霉烷酸偶联。为了进入真菌细胞，苯乙酸必须穿过质膜。本研究在菌丝体和脂质体中研究了苯乙酸穿过质膜的过程。菌丝体对苯乙酸的摄取是非饱和的，随着外部 pH 值的降低，初始速度呈对数增加。脂质体研究表明，质子化物质通过脂质体膜的快速被动通量。这些结果表明，苯乙酸通过质子化物质的被动扩散穿过质膜。在 3mM 的外部浓度下，苯乙酸的摄取速率至少比 Panlabs P2 菌株中青霉素 G 的生产速率高 200 倍。在该菌株中，苯乙酸的摄取不是青霉素 G 生物合成的限速步骤。
