S Preparation
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The glucose-tolerant (GT) strain of Synech … The glucose-tolerant (GT) strain of Synechocystis sp. PCC 6803, isolated by Williams, and the SigE-overexpressing strain were grown in BG-110 liquid medium with 5 mM NH4Cl (buffered with 20 mM Hepes-KOH (pH 7.8)), termed modified BG-11 medium. Liquid cultures were bubbled with 1% (v/v) CO2 in air at 30 °C under continuous white light (∼50–70 μmol photons m−2 s−1). For plate cultures, modified BG-110 (the concentration of NH4Cl was 10 mM instead of 5 mM in liquid medium) was solidified using 1.5% (w/v) agar (BD Biosciences) and incubated in air at 30 °C under continuous white light (∼ 50–70 μmol photons m−2 s−1). The null mutant of sigE, named G50, was generated as published previously. For the SigE-overexpressing strain and the sigE null mutant, 20 μg/ml kanamycin (Sigma) was supplemented in the modified BG-11 liquid medium. Dark conditions were achieved by wrapping culture plates with aluminum foil. Growth and cell densities were measured at A730 with a Beckman DU640 spectrophotometer. 30 with a Beckman DU640 spectrophotometer.
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