For prokaryotes, bacteriophages and other plasmids, experiments could be performed in minimal risk containment facilities when the construction of recombinant DNA molecules and their propagation involved prokaryotic agents that were known to exchange genetic information naturally. For experiments involving the creation and propagation of recombinant DNA molecules from DNAs of species that ordinarily did not exchange genetic information and generate novel biotypes, the experiments were to be performed in at least in a low risk containment facility. If the experiment increased the pathogenicity of the recipient species or result in new metabolic pathways in species, then moderate or high-risk containment facilities were to be used. In experiments where the range of resistance of established human pathogens to therapeutically useful antibiotics or disinfectants was extended, the experiments were to be undertaken only in moderate or high-risk containment facilities.