Rudin L, Sjöström J E, Lindberg M, Philipson L
J Bacteriol. 1974 Apr;118(1):155-64. doi: 10.1128/jb.118.1.155-164.1974.
A chemically defined medium has been developed for isolation of amino acid-requiring mutants of Staphylococcus aureus strain 8325, and for use as a selective medium in transformation assays. Variables affecting transformation of both plasmid and chromosomal markers have been studied. The optimal pH and temperature for transformation are 6.75 to 7.0 and 30 C, respectively. Ca ions are required for transformation, and only cells lysogenic for the phage phi11 can be transformed. Superinfection of competent cells with phi11 does not increase the transformation frequency. Maximal number of transformants is obtained after 20 min of contact between cells and deoxyribonucleic acid. The transformation frequencies for the plasmid marker erythromycin resistance (ero) and the chromosomal markers trp, thy, and cyt are of the same order of magnitude, whereas the frequency for the chromosomal marker tyr is approximately one order of magnitude lower.
已开发出一种化学成分明确的培养基，用于分离金黄色葡萄球菌8325株的氨基酸需求突变体，并用作转化试验中的选择培养基。研究了影响质粒和染色体标记转化的变量。转化的最佳pH值和温度分别为6.75至7.0和30℃。转化需要钙离子，并且只有对噬菌体phi11溶原的细胞才能被转化。用phi11对感受态细胞进行超感染不会增加转化频率。细胞与脱氧核糖核酸接触20分钟后可获得最大数量的转化体。质粒标记红霉素抗性（ero）和染色体标记trp、thy和cyt的转化频率处于相同数量级，而染色体标记tyr的频率大约低一个数量级。
