3. Outdoor cultures in panel photobioreactors
C. protothecoides CS-41 was grown in outdoor panel photobioreactors
(PBRs) in Shanghai, China (latitude 31 140 N, longitude
121 290 E). The reactors are 140-cm high and 120-cm long with
an internal width of 3.5 cm. Compressed air was bubbled at the
bottom of the reactors through a perforated plastic tube to produce
a turbulent flow in the culture suspension. A stainless iron tube
with circulation of cooling water was placed in the cultures to prevent
the culture temperature from exceeding 30 C. During the
night, the cooling system was turned off and the culture temperature
was allowed to equilibrate to ambient. The seed cultures were
maintained in 20-L indoor panel PBRs with continuous illumination
of 100 lE m2 s1 to late exponential growth phase and inoculated
into outdoor panel PBRs at 6:00 PM (day 0). Cell samples
were collected every day at 6:00 PM for analyses. Light intensity
was monitored by a quantum sensor (Li-Cor LI-190), which was
attached to the surface center of both PBR sides and connected to
a Li-Cor LI-1400 data logger.