ABSTRACT
The need for efficient hosts for heterologous enzyme production is of paramount importance in any protein-engineering program and molds now offer systems that can compete with, and sometimes surpass, bacterial, yeast, and viral expression systems. Despite the success in exploiting molds as hosts for heterologous enzyme production, there are considerable difficulties still to be overcome before such systems become user-friendly to the extent that a new target enzyme can be expressed and secreted at predictably high yields. Also, the use of waste materials as substrates for growth of the host mold must become a serious consideration, and the ability of molds to grow on a range of solid and semisolid materials can only increase the interest paid to them as potential hosts for enzyme production. An autonomously replicating plasmid has been described that transforms A. nidulans at a frequency of 20,000 transformations per 10 protoplasts at high levels of transforming DNA (ca 300 ng DNA).
