SCANNING ELECTRON-MICROSCOPY OF IMMOBILIZED HUMICOLA-LUTEA DURING SEMICONTINUOUS PRODUCTION OF ACID PROTEINASES

The morphology of the fungus Humicola lutea (strain 120-5), immobilize d in polyacrylamide and polyhydroxyethylmethacrylate and used for the semicontinuous production of acid proteinases, was examined by scannin g electron microscopy. The fungus developed a dense mycelium below the bead surface as well as in the bead interior after precultivation of entrapped spores. During maximal semicontinuous enzyme biosynthesis, f ormation of numerous large bulbous cells with a different shape was ob served. Lysis of the cells was observed mainly in the centre of the ge l beads after 13 successive fermentations with polyacrylamide-immobili zed cells or after 21 re-uses of polyhydroxyethylmethacrylate-immobili zed mycelia, respectively. Growth and changes in the cellular morpholo gy of immobilized H. lutea, accompanying biosynthesis of acid proteina ses, were comparable in both gel matrices but mycelia immobilized in p olyhydroxyethylmethacrylate maintained their productivity twice as lon g.