Fig. 5

Comparison of the efficiency of DNA release from M. smegmatis cells by procedures in current use. A and B are results from two separate experiments. Acid in A and B indicates standard treatment with acid/alkali. a DNA release from 6×10⁹ M. smegmatis by bead-beating and boiling. > initial treatment was followed by a second treatment as indicated after the symbol. BB, bead-beating; SDS + BB, bead-beating of cells suspended in 1.0 % SDS; boil, suspension heated at 100 °C for the indicated time; Freeze-boil, cell suspension frozen at −20 °C, then heated at 100 °C for 10 min; ×2, cycle repeated once. b DNA release from 9×10⁹ M. smegmatis by guanidine hydrochloride. Cell suspension heated at 100 °C for 10 min in: GuHCl + rTX100, 8 M guanidine hydrochloride, 2 % reduced triton X-100, 80 mM Tris–HCl, 40 mM CDTA, pH 8.0; rTX100, 2 % reduced triton X-100, 80 mM Tris–HCl, 40 mM CDTA, pH 8.0; Water, water. c DNA released from M. smegmatis by bead-beating in combination with boiling or detergents. BB, bead-beating; boil, suspension heated at 100 °C for 10 min; rTX100, 2 % reduced triton X-100; 1 % F68, pluronic F-68. See Methods for additional details. Error bars represent the mean ± range of duplicate samples. Both ‘rT100’ and ‘boil > BB’ are significantly different from ‘BB’ (P < 0.05, unpaired t-test)