1、普通使用的抗生素的貯液和工作液濃度下面的內容摘自分子克隆第三版 附錄2以水為溶劑的抗生素貯存液應用0.22 m濾器過濾除菌；用乙醇溶解的抗生素溶液無須過濾除菌；所有抗生素貯液都應放于不透光的容器中保存。注意：鎂離子是四環素的拮抗劑。對于以四環素為篩選抗性的細菌，應使用不含鎂離子的培養基，如LB培養基。下面是常用抗生素的貯液濃度及工作濃度氨芐青霉素   貯液濃度   50 mg/ml  溶于水  -20保存  工作濃度 20 g/ml （嚴緊型質粒） 60 g/ml （松弛型質粒）羧芐青霉素   貯液濃度&

2、#160;  50 mg/ml  溶于水  -20保存  工作濃度 20 g/ml （嚴緊型質粒） 60 g/ml （松弛型質粒）氯霉素         貯液濃度   34 mg/ml  溶于乙醇  -20保存  工作濃度 25 g/ml （嚴緊型質粒） 170 g/ml （松弛型質粒）卡那霉素      貯液濃度   10 mg/ml  溶于水&

3、#160; -20保存  工作濃度 10 g/ml （嚴緊型質粒） 50 g/ml （松弛型質粒）鏈霉素         貯液濃度   50 mg/ml  溶于水  -20保存  工作濃度 10 g/ml （嚴緊型質粒） 50 g/ml （松弛型質粒）四環素         貯液濃度   5 mg/ml  溶于乙醇  -20保存 

4、; 工作濃度 10 g/ml （嚴緊型質粒） 50 g/ml （松弛型質粒）利福平，Rifampicin (INN) 簡寫為Rif。分子式：C43H58N4O12，相對分子質量為822.94022 g/mol。 化學名 3-(4-甲基-1-哌嗪基)亞氨基甲基-利福霉素利福平是一種半人工合成的抗生素，最初從地中海氏擬無枝菌酸菌（Amycolatopsis mediterranei）中獲得。利福平為利福霉素類半合成廣譜抗菌藥，對多種病原微生物均有抗菌活性。該藥對結核分枝桿菌和部分非結核分枝桿菌（包括麻風分枝桿菌等）在宿主細胞內外均有明顯的殺菌作用。利福平對需氧革蘭陽性菌具良好抗菌作用，包

5、括葡萄球菌產酶株及甲氧西林耐藥株、肺炎鏈球菌、其他鏈球菌屬、腸球菌屬、李斯特菌屬、炭疽桿菌、產氣莢膜桿菌、白喉桿菌、厭氧球菌等。利福平分子結構圖實驗用利福平溶液的配制1. 50 mg/mL stock solution in methanol.2. Vortex immediately to prevent rifampicin from sticking to bottom of tube.3. Add 5 drops 10 N NaOH per mL to facilitate dissolving.4. Add 2 mL per liter of culture to achieve a

6、 working concentration of 100 g/mL.也可以采用下面的配制方法：Alternately, dissolve 50mg/mL in DMSO and vortex to suspend. In this form, you don't need NaOH. Store at -20°C.利福平易溶于有機溶劑，難溶于水，見下表。注意事項：（對光敏感；半衰期短）Rifampicin is light-sensitive so store stock solution, plates and media in the dark and wrap in

7、foil. It also degrades in solution fairly quickly, so make stocks and replace them every couple months. （操作利福平平板時要避光！）利福平的抑菌機制利福平與依賴DNA的RNA聚合酶的亞基牢固結合，阻止該酶與DNA的結合，從而阻斷RNA轉錄過程，使蛋白質無法合成。Rifampicin interacts with the subunit of RNA polymerase when it is in an 2 trimer. This halts mRNA transcription, the

8、refore preventing translation of polypeptides. The Rifampin-RNA polymerase complex is extremely stable and yet experiments have shown that this is not due to any form of covalent linkage. It is hypothesized that hydrogen bonds and - bond interactions between naphthoquinone and the aromatic amino aci

9、ds are the major stabilizers, though this requires the oxidation of naphthohydroquinone which is found most commonly in Rifampin. It is this last hypothesis that explains the explosion of multi-drug-resistant bacteria: mutations in the rpoB gene that replace phenylalanine, tryptophan, and tyrosine w

10、ith non-aromatic amino acids result in poor bonding between Rifampin and the RNA polymerase.細菌耐利福平的分子機制細菌可以自發獲得對利福平的耐藥性，最常見的方式是rpoB基因發生突變。rpoB基因即編碼RNA聚合酶亞基的基因。突變的類型可能是某個堿基的改變造成氨基酸的替換、一小段DNA的插入或缺失。由于rpoB基因的突變是隨機發生的，可以根據細菌在某種條件下產生耐利福平的幾率還計算這種細菌在該條件下的突變率。rpoB is a bacterial gene that codes for part of an enzyme which synthesises RNA. Specifically, rpoB is the subunit of the bacterial RNA polymerase. It is the subunit which possesses the polymerase activity, that is,