 mechan genet recombin transform bacillu subtili molecular fate transform dna compet bacillu subtili studi physic differenti transform dna genet materi recipi bacteria effect emploi isotop compet bacteria label allow incorpor p-label transform dna intracellularli dna isol recipi cell centrifug cesium chlorid analysi drop fraction collect equilibrium presenc radioact region densiti correspond recipi dna materi contribut donor dna resid dna occur genet inert bacillu cereu dna substitut homolog dna conclud radioact appear unlabel resid dna result degrad input dna subsequ incorpor normal metabol process singl-strand dna donor origin detect evid non-specif aggreg donor recipi dna conclud observ physic associ transform recipi dna occur result genet recombin transform subtili 