Fig. 3.
Characterization of engineered sucrose-producing Synechocystis strains grown under continuous 200 μmol photons m−2 s−1 light. The strains S01 (over-expression of sucrose permease CscB) and S01:Δflv3 (over-expression of CscB and inactivation of flavodiiron protein Flv3) were evaluated in respect to (a) sucrose production (mg l−1) and (b) growth (OD750nm) and (c, d) gas flux rates. In a and b, the control strain S01 is shown in grey and the strain S01:Δflv3 in brown. In c and d, the lines represent the gross O2 evolution (black), O2 uptake (red), total carbon uptake (blue) and net O2 evolution (magenta) measured on day 5 as a function of irradiance for the strains S01 and S01:Δflv3, respectively. The irradiance corresponding to the growth light intensity is highlighted in yellow. To assist the comparison between c and d, the zero gas flux level and the S01 control strain total carbon uptake level at 500 μmol photons m−2 s−1 have been shown in horizontal dashed line and dotted line, respectively (see Additional file 1: Table S1 for calculated statistical comparison). The strains were cultivated in 1% CO2 in the presence of 400 mM supplemented NaCl. In each case, the average and standard deviation were calculated from three to four independent experiments