Startup: Phase I
The biomass growth profiles of Arthrospira under photoautotrophic
conditions in three phases are shown in Figure 2. In Phase I, the growth
response to constant low temperature (LT) (20 °C±1) (AB & CD) and high
temperature (HT) (35°C±1) (EF & GH) was assessed. PBRs were cultivated
in batch mode for initial 5 days to reach OD750 2.0 and
beyond, and then operated in semi-continuous mode maintaining the
OD750 = 2.0 starting point from day 5 to 15 with
harvest/dilution every two days. For the chosen temperatures of 20°C and
35°C, the average pre-dilution concentrations of the cultures were 1.30
gDW L-1 (OD750 = 2.6) and 1.62 gDW
L-1 (OD750 = 3.2) respectively (Figure
2) yielding biomass growth rates 0.17 gDW L-1d-1 and 0.20 gDW L-1d-1 at 20 °C and 35 °C, respectively. These results
are summarized in Table 1. As can be seen in the table, good
reproducibility is found for all results (including pigment contents to
be discussed later).