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
OD750 = 2.0 starting point from day 5 to 15 with
harvest/dilution every alternate day.
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-1 d-1 and
0.20 gDW L-1 d-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).