Figure 2.

Fluorescence of recombinant C. glutamicum strains expressing gfp variants. Shown is ATCC 13032/pEKEx2-gfpuv (black), ATCC 13032/pEKEx2-gfpuv-aav (patterned), ATCC 13032/pEKEx2-gfpuv-asv (grey) and ATCC 13032/pEKEx2 (white) as control. Cells were cultivated in CGXII minimal medium containing 1 mM IPTG to an OD₆₀₀ of 3–5; 2 ml of cells were harvested by centrifugation and subsequently frozen in liquid nitrogen. Fluorescence was determined using Fluorolog 3 Double Spectrometer (Spex, USA). For this purpose, cells were thawed on ice, resuspended in 10 ml of cold TE buffer (10 mM Tris, 1 mM EDTA, pH 7.5) and the OD₆₀₀ was determined. GFPuv fluorescence was carried out in triplicates using an excitation wavelength of 395 nm and recording emission at 509 nm. The graph shows the mean maximum fluorescence referred to the cell dry weight (1 ml of cell suspension of an OD₆₀₀ of 1 corresponds to 0.36 mg of dry weight).