Gene replacement and ectopic integration in the zygomycete Mucor circinelloides.

Transformation of Mucor circinelloides with plasmid pTL42 led to the identification of different integrative events. Analysis of eight transformed strains allowed the detection of three classes of transformants: integrative types derived from either homologous (exclusively at the leuA locus) or heterologous recombination and a class which originated by gene replacement. No autonomous replication of the vector was observed.