Fractionation of Transformable Bacteria from Competent Cultures of Bacillus subtilis on Renografin Gradients

Florence Haseltine Cahn, Maurice S. Fox
1968 Journal of Bacteriology  
Growth medium 1 (1; C. D. Laird, Ph.D. Thesis, Stanford Univ., Palo Alto, Calif., 1966) was LS medium containing 20 ,ug/mil of all the common L-amino acids except arginine, lysine, methionine, and cystine (10) plus 0.5% glucose. Growth medium 2 was LS medium supplemented with 0.5% glucose, 0.02% Vitamin Free Casamino Acids, 20 ug/ml each of L-phenylalanine, L-tyrosine, L-tryptophan, and L-histidine, and 0.02 pg/m each of p-hydroxybenzoic acid and p-aminobenzoic acid, as described by C. D.
more » ... ibed by C. D. Laird. A competent culture was prepared from an overnight culture of SB 25 (his-2 trp-2) grown in Penassay broth at 37 C. The bacteria were centrifuged at 9,000 X g in a Servall SS 34 rotor for 10 min, and the packed cells were resuspended at a density of 5 X 107 bacteria/ml in growth medium 1. These bacteria were grown to stationary phase (4.5 to 6 hr at 37 C); dimethyl sulfoxide was added to 5% by volume, and portions were frozen in an ethyl alcohol-dry ice bath. 867 on May 4, 2020 by guest
doi:10.1128/jb.95.3.867-875.1968 fatcat:dlpnbim7wbclhhd4gegvlkcpwq