DNA shuffling mimics an accelerated evolutionary process that selects for improved individuals. DNA shuffling allows for recombination between multiple parents at each generation, resulting in 'complex progeny' and faster selection. In the February 7 Nature Ying-Xin Zhang and colleagues at Maxygen in California describe using a whole-genome shuffling approach to derive new bacterial strains (Nature 2002, 415:644-646). They chose to shuffle Streptomyces, used to produce commercial antibiotics. Zhang et al. carried out repeated rounds of protoplast fusions on mixtures of four Streptomyces strains and demonstrated that genome shuffling could accelerate directed evolution. They applied the method to Streptomyces fradiae strains that produce the antibiotic tylosin, and generated superior tylosin-producing strains after just two rounds of genome shuffling - much faster than traditional sequential random mutagenesis methods.