Fig. 2
Expression leakage of GFPuv in E. coli BL21(DE3) [pET21d(+)-gfpuv] cells on media of various compositions. The cultures were grown at 37 °C in A M9 minimal medium and variants of LB medium. The tested LB media contained yeast extract and NaCl, supplemented with the tested peptones; B control culture, grown in a medium without a peptone; C medium with soya peptone added; and D tryptone peptone. Samples were taken at 1-h intervals, starting when the cultures reached OD600  = 0.6–0.8, and were then subjected to spectrophotometric and SDS-PAGE analysis. Bacterial cells were lysed and analysed using a 10% gel. (Lane M) Pierce™ Unstained Protein MW Marker (Thermo Scientific); (Lane K) purified recombinant GFPuv protein; (Lane T0) E. coli BL21(DE3) [pET21d(+)-gfpuv] cells at OD600  = 0.6–0.8; (Lane T1) cells 1 h after the culture reached OD600  = 0.6–0.8; (Lane T2) 2 h; (Lane T3) 3 h; (Lane T4) 4 h; (Lane T5) 5 h; and (Lane TO/N) cells after overnight cultivation. The arrows indicate the position (26.8 kDa) at which GFPuv migrates in the gel. The red arrow indicates GFPuv in the samples containing the expressed gfpuv gene