Figure 6.

Production of Extracellular Hydrogen Peroxide and Accumulation of FLVs by Wild-Type and pgrl1 Lines Grown under Different Light and CO₂ Conditions.

(A) and (B) Measurements were performed on cells grown photoautotrophically in batch cultures supplied with 2% CO₂ in air or with air in the presence of LL (50 μmol photons m⁻² s⁻¹) or HL (200 μmol photons m⁻² s⁻¹). Hydrogen peroxide concentration was assessed in culture medium using Amplex red by measuring fluorescence emission at 580 nm. Wild-type progenitor (dark bars) and pgrl1 (white bars) lines. Shown are means ± sd (n = 3).

(C) and (D) Accumulation of the FLV proteins was determined by immunoblot analysis of wild-type and pgrl1 lines grown in photobioreactors operated as turbidostats at a constant biomass concentration (≈1.5 × 10⁶ cells mL⁻¹). The cultures were grown in 120 μmol photons m⁻² s⁻¹ (LL) or 500 μmol photons m⁻² s⁻¹ (HL) light intensity and in the presence of 2% CO₂ in air (C) or in air (D). The FLVB protein has a size of ∼60 kD and FLVA shows the faint band at ∼70 kD. Fifteen micrograms of total protein as 100% was loaded per lane, and from the pgrl1 mutant 50 and 25% were loaded as well.