This paper reviewed the effect of oxygen concentration on the growth of Nannochloropsis sp. at low light intensity. The experiment manipulated the dissolved oxygen level from 25% to 300% air saturation in a flat panel photobioreactor. The results showed that increasing the oxygen concentration from 20% to 75% air saturation had no obvious effect on the microalgae's specific growth rate. To improve productivity, the oxygen level needs to be controlled. Further research is needed to investigate the synergistic effects of high irradiance and oxygen concentration on optimizing microalgae growth and productivity in closed photobioreactors.

1. PAPER REVIEW
Effect of oxygen concentration on the growth
of Nannochloropsis sp. at low light intensity.
Name : Vijendren Krishnan
Supervisor : Prof. Dr. Yoshimitsu Uemura
Date : 16 July 2014

2. 2

3. INTRODUCTION
CO2, nitrogen and phosphate content have
been known to influence growth and lipid
production
Oxygen may cause deleterious effect to
microalgae especially in tubular PBR.
Photorespiration & Photo-inhibition may
decrease the microalgae growth
3

4. CALVIN CYCLE
4

5. CHANGE IN MECHANISM
5

6. EXPERIMENTAL
Culture condition:
Light : 18:6hr, 41 μmol photon m-2 s-1 (Red LED,
637nm)
pH : 7.8
CO2 : 2%
Flow rate : 0.5 L/min
Medium : Zou medium
PBR : Flat panel PBR
6

7. ZOU MEDIUM
7

8. EXPERIMENTAL
Manipulated: Dissolved oxygen (air saturation):
25, 50, 75, 100, 125, 150, 175, 200, 250, 300%
Responding :
* Oxygen evolved (photosynthetic rate) 
liquid phase oxygen electrode chamber
* Biomass dw  pre-weight glass microfibre
filter, washed with ammonium formate (O.5M)
8

9. RESULT AND DISCUSSION
9

10. Figure 2 : A typical growth curve of Nannochloropsis sp. During the batch run in a 1.5-L
flat-panel photobioreactor, followed by the turbidostat run at dissolved oxygen (DO)
concentration ranging from 20 to 100% air saturation; a batch, b 100% DO, c 75% DO, d
50% DO, e 25% DO, f 20% DO 10

11. 11

12. 100% C1.77O0.24N0.15
300% C1.72O0.24N0.15
12

13. Table 2: of oxygen effects on growth of Nannochloropsis sp. At different oxygen
concentrations
13

14. CONCLUSION
An increase of the oxygen concentration from
20 to 75% air saturation showed no obvious
effect of oxygen concentration on specific
growth rate.
To improve the productivity of Nannochloropsis
sp. the oxygen level needs to be controlled.
Synergetic effects of high irradiance and oxygen
on growth for optimization of productivity in the
closed photobioreactors need to be
investigated..
14