The ultrastructure of Penicillium chrysogenum in the course of benzyl-penicillin biosynthesis.

The find structures of high- and low-yield mutants of Penicillium chrysogenum, producing 100 and 10,000 units/ml of penicillin G, were compared. The cells of both mutants demonstrated a typical eukaryotic ultrastructure. In the cytoplasm nuclei, mitochondira, lipid bodies, endoplasmic reticulum, and Golgi vesicles were observed. In the cells of high-yield mutant, during the biosynthesis of penicillin, the number of lipid bodies decreased. It is possible that the lipids are metabolized in the process of biosynthesis of penicillin. In the cytoplasm more multivesicular bodies and small vesicles, about 40 nm in diameter, could be seen. These Golgi vesicles, present in largest number in cells of high-yield mutant, fuse with the cell membrane and play an important role in the transport of penicillin from the cytoplasm to the cell environment. The cell walls of the high-yield mutant become three times thicker during the antibiotic biosynthesis. No comparable changes were observed in the ultrastructure of the low-yield mutant. The cell wall thickness did not increase, the cytoplasm contained few Golgi vesicles only, and the lipid bodies can be seen in all cells.