Antibiotic used include kenamycin, ampicillin and tetracycline. This is useful to determine if and which bacteria took up the plasmid as they were supposed to during the process of recombination. Host bacteria are normally killed by these antibiotics. If the recombinant plasmids were taken up by the bacteria, plasmid may have contained a DNA gene for resisting the effects of one or more antibiotics. Host bacteria are placed in a growth medium containing an antibiotic to which they have a resistant gene in their recombinant plasmid DNA survivor. If they havent taken the plasmid they die.