DNA-MEDIATED TRANSFORMATION OF A FUNGUS EMPLOYING A VECTOR DEVOID OF BACTERIAL-DNA SEQUENCES

Acremonium chrysogenum, a producer of cephalosporin C, was subjected t o DNA-mediated transformations using a Vector without bacterial DNA se quences. Recombinant fungal strains were generated with a gel-purified DNA fragment, carrying only the mutated P-tubulin gene from A. chryso genum. The lack of any bacterial DNA was verified by Southern hybridiz ation analysis and polymerase chain reaction amplifications to detect even residual DNA sequences. This procedure can be referred to as a se lf-cloning experiment for which less restricted working regulations ar e needed. Finally, the transfer of a synthetic hirudin gene by cotrans formation demonstrated that any DNA molecule can be introduced into th e A. chrysogenum genome without bacterial marker genes. This seems to be highly relevant for biotechnical processes in which safe recombinan t producer strains are required to satisfy governmental restrictions.