Improved production of extracellular α-amylase, by the thermophilic fungusMalbranchea sulfurea, following protoplast fusion.

Protoplasts of a catabolite-repression-resistant strain ofMalbranchea sulfurea and a mutant of it over-producing amylase were isolated and fused using electrofusion. The yield of hybrids was 5×10(-5). One stable hybrid, DGCS 1, was insensitive to glucose repression and produced approx. twice the α-amylase activity produced by either of its parents. The amount of DNA in DGCS 1 was also double that of either parent strain.