Antibiotics

Working concentrations and stock solutions.

Stock solution Working concentration: Strict control Weak control mg/ml: µg/ml dilution µg/ml dilution Ampicillin 50 (H2O*) -20oC 20 0.4 µl/ml 60-125 1.2-2.5 µl/ml Carbenicillin 50 (H2O, 50%EtOH) -20oC 20 0.4 µl/ml 60-200 1.2-4 µl/ml Chloramphenicol 34 (EtOH, MetOH) -20oC 25 0.7 µl/ml 170 5 µl/ml D-cycloserine* 10 (0.1M NaP pH8.0) 4oC 200 20 µl/ml Gentamycin 10 (H2O) -20oC 15 1.5 µl/ml Hygromycin B 10 (H2O) -20oC 10 1 µl/ml 400 40 µl/ml Kanamicin 50 (H2O) 4oC- -20oC 10 0.2 µl/ml 50 1 µl/ml Kasugamycin 10 (H2O) -20oC 1000 100 µl/ml Nalidixic acid 5 (H2O,pH to 11 /NaOH) -20oC 15 3.0 µl/ml Neomycin 10 (H2O) -20oC 100 10 µl/ml 800 80 µl/ml Rifampicin** 34 (MetOH) -20oC 150 4.4 µl/ml Spectinomycin 10 (H2O) -20oC 100 10 µl/ml Streptomicin 50 (H2O) -20oC 10 0.2 µl/ml 50 1 µl/ml Tetracycline*** 5 - 12.5 (EtOH, 70%EtOH) -20oC 10 2 µl/ml 50 100 10 µl/ml 20 µl/ml

Unstable solution, prepare just before use;
** - Light sensitive;
*** - Light sensitive, Mg² - inhibitor;

Preparation of stock solutions. Ampicillin. Conc. 1ml 5ml 10ml Ampicillin 50mg/ml 50mg 250mg 0.5g H2O 1ml 5ml 10ml filter sterilization; or preparation from the sterile water and the sterile powder; store at -20oC in small quantities (about 10 freezing-thawing cycles); instead of H2O it is possible to use 50% glycerol. The advantage - solution is liquid at -20oC. some laboratories use 96% (or 50%) EtOH for ampicillin solubilization. There are two advantages in this method: (i) solution is liquid at -20oC, (ii) the solution is self sterilizing. But the disadvantage it very serious: ethanol is a weak catalyst of b-lactam ring disruption. So, solution is unstable. Carbenicillin. Conc. 1ml 5ml 10ml Carbenicillin 50mg/ml 50mg 250mg 0.5g H2O 1ml 5ml 10ml filter sterilization; or preparation from the sterile water and the sterile powder; store at -20oC in small quantities (about 10 freezing-thawing cycles); 200 µg/ml for pETpfu. Chloramphenicol. Conc. 1ml 5ml 10ml Chloramphenicol 34mg/ml 34mg 170mg 340mg store dry powder at 4oC, solution at -20oC (in EtOH); BL21(DE3)pLyzS - 34µg/ml -> 1µl for 1ml of medium. GE antibiotic mix (50x). Conc. 40ml Cefotaxime 25µg/ml 25µg/ml 1mg Ceftriaxone 25µg/ml 25µg/ml 1mg KPO4(pH 6.0) 0.1M 40ml filter sterilization; or preparation from the sterile KPO4 and the sterile powder; store at -200C, in small quantities (about 10 freezing-thawing cycles). Tetracycline. Conc. 1ml 5ml 10ml Tetracycline 5mg/ml 5mg 25mg 50mg EtOH 1ml 5ml 10ml solution in EtOH, store at -20oC. Mg- antagonist, for the selection it is necessary to use Mg-free medium.