Fig. 3

Strategy for construction of large-deletion mutants by optimized Cre/loxP system. Two nonessential gene regions (499,650–1,841,266 bp, 7,994,797–8,731,201 bp) are selected as candidate targeted deletion regions based on comparative genomic analysis. LoxP mutant site lox71 is introduced into genome by pKC1139-mediated double crossover. Another loxP mutant site lox66 is introduced into genome by suicide vector-mediated single crossover. Expression of Cre enzyme is induced by 0.1% ε-caprolactam to mediate site-specific recombination between lox71 and lox66 after pNitCre is introduced