GENE REPLACEMENT IN THE LIGNIN-DEGRADING BASIDIOMYCETE PHANEROCHAETE-CHRYSOSPORIUM

The ability to carry out gene replacements and gene targeting in the l ignin-degrading basidiomycete fungus, Phanerochaete chrysosporium, wou ld facilitate studies on the roles and regulation of various component s of its lignin-degrading system. A plasmid consisting of the P. chrys osporium ura3 gene (encoding orotidylate decarboxylase) interrupted wi th the Schizophyllum commune ade2 gene (encoding an adenine biosynthet ic enzyme) was used to transform the P. chrysosporium ade2 strain to a denine prototrophy with selection on 5-fluoroorotic acid for inactivat ion of the ura3 gene. Stable Ade(+)Ura(-) strains were obtained at a f requency of approximately one transformant per mu g of DNA. In all of the Ade(+)Ura(-) transformants examined by Southern analysis, the chro mosomal ura3 locus had been replaced by the plasmid insert.