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Formation and properties of protoplasts from antibiotic-producing strains of Penicillium chrysogenum and Cephalosporium acremonium.

SUMMARY: Osmotically fragile protoplasts have been prepared by the action of lytic enzymes on the mycelium of Penicillium chrysogenum and Cephalosporium acremonium. The yield of protoplasts, based on DNA content, was up to 18 %. Pretreatment of the mycelium with a thiol compound was necessary with Cephalosporium but not with Penicillium. Electron micrographs indicated that the protoplasts contained all the intracellular organelles of the mycelium and were bounded only by a cytoplasmic membrane. The metabolic activity of the protoplasts, as measured by their respiration, ability to maintain intracellular amino-acid pools, and antibiotic production, was similar to that of control mycelium. l-Valine and l-α-aminoadipic acid, which are precursors of penicillin N and cephalosporin C, were taken up and concentrated by the protoplasts of C. acremonium, although the latter transported l-valine less rapidly than did the corresponding mycelium. Protoplasts of P. chrysogenum took up l-valine but not l-α-aminoadipic acid or its δ-ester. There was little or no transport of the corresponding d-amino acids by protoplasts of either organism.