Fig. 1

Outline of the genome shuffling experiment. Wild-type haploid cells of both mating types were UV irradiated to generate pools of haploid mutants. Mutants with tolerance to hydrolysate superior to their wild-type ancestors were selected using plates displaying a gradient of hydrolysate concentration. The pools of tolerant haploid mutants thus obtained were mated, generating diploids. Tolerant diploids were selected on gradient plates, and sporulated. Resulting haploids were mated at random, effecting the shuffling of mutations. Five cycles of diploid selection on gradient plates, sporulation and mating were performed. Genomic DNA from each round of shuffling and selection was submitted to population genome sequencing and mutation analysis