Fig. 5
From: Engineering of the fast-growing cyanobacterium Synechococcus sp. PCC 11901 to synthesize astaxanthin
Astaxanthin and biomass accumulation of cyanobacterial transformant. a Accumulation of astaxanthin in BC cultures grown in batch mode for 10 days in 80-ml airlift PBRs. Samples were collected on days 3, 4, 7, and 10. Cells were exposed to an initial gradient of white light, reaching 1500 µmol/m2/s at day 2. Statistical significance is expressed by different letters according to Tukey–Kramer test (n = 4). b Growth curves of BC lines cultivated in batch mode in 80-ml airlift PBRs, using OD720 as an index of cell density. Cultures were exposed to 250 µmol/m2/s of white light for the first 6 h. The light was then increased following a stepwise gradient (1 h to increase light intensity to the next level of light intensity, which was kept for 6 h, and then this whole step was further replicated until reaching the desired light intensity). Final light intensities reached in the 4 tested conditions were 250 µmol/m2/s, 750 µmol/m2/s, 1500 µmol/m2/s, and 2250 µmol/m2/s. Two independent cultures per condition were evaluated. Error bars represented standard deviation (n = 4). c OD720 of samples described in a: samples were diluted accordingly below 1 before measurements to avoid saturation. Error bars represented standard deviation (n = 4)