GENE REPLACEMENT IN THE LIGNIN-DEGRADING BASIDIOMYCETE PHANEROCHAETE-CHRYSOSPORIUM

The ability to carry out gene replacements and gene targeting in the lignin-degrading basidiomycete fungus, Phanerochaete chrysosporium, would facilitate studies on the roles and regulation of various components of its lignin-degrading system. A plasmid consisting of the P. chrysosporium ura3 gene (encoding orotidylate decarboxylase) interrupted with the Schizophyllum commune ade2 gene (encoding an adenine biosynthetic enzyme) was used to transform the P. chrysosporium ade2 strain to adenine prototrophy with selection on 5-fluoroorotic acid for inactivation of the ura3 gene. Stable Ade(+)Ura(-) strains were obtained at a frequency of approximately one transformant per mu g of DNA. In all of the Ade(+)Ura(-) transformants examined by Southern analysis, the chromosomal ura3 locus had been replaced by the plasmid insert.