Antibiotics commonly used with bacterial plasmids for growth in E. Coli
Antibiotic
| Stock Concentration
| Storage
| Working Concentration
| Dilution |
ampicillin
| 50 mg/ml in water
| -20C
| 100 μg/ml
| 1:500 |
chloramphenicol
| 34 mg/ml in ethanol
| -20C
| 170 μg/ml
| 1:200 |
kanamycin
| 10 mg/ml in water
| -20C
| 50 μg/ml
| 1:200 |
streptomycin
| 10 mg/ml in water
| -20C
| 50 μg/ml
| 1:200 |
tetracycline
| 5 mg/ml in ethanol
| -20C
| 50 μg/ml
| 1:100 |
carbenicillin
| 50 mg/ml in water
| -20C
| 50 μg/ml
| 1:1000 |
zeocin
| 100 mg/ml in water
| -20C
| 25 μg/ml
| 1:4000 |
Be sure that media (eg LuriaBroth) has cooled to 50C or less before adding antibiotics. At this temperature, the container should feel very hot, but should be able to be held in bare hands.
Low Copy Plasmids
Most modern plasmids have been heavily modified to achieve very high copy number in bacterial cells. Older plasmids (based on naturally occurring plasmid sequences) are low in copy number, usually around 5 copies per cell. If using a low copy number plasmid, reduce the amount of antibiotics added
Antibiotic
| Working Concentration |
ampilcillin
| 20 μg/ml |
chloramphenicol
| 25 μg/ml |
kanamycin
| 10 μg/ml |
streptomycin
| 10 μg/ml |
tetracycline
| 10 μg/ml |
carbenicillin
| 20 μg/ml |