Dissertation
EVALUATION AND OPTIMIZATION OF CULTIVATION CONDITIONS AND PARAMETERIZATION OF A LIGHT DISTRIBUTION MODEL FOR GREEN CELL GROWTH OF THE MICROALGAE: HAEMATOCOCCUS PLUVIALIS UNDER AUTOTROPHIC CONDITIONS
Doctor of Philosophy (PhD), Washington State University
01/2016
Handle:
https://hdl.handle.net/2376/117197
Abstract
Haematococcus pluvialis is one of the best sources of astaxanthin. However, this green microalga grows slowly and has a low cell density under normal conditions. Prior research focused mostly on the red stage, few studies have explored the green stage, when these algae gain biomass before astaxanthin accumulation.
Focusing on green stage cultivation, this study found that artificial light application could be improved by applying a combination of red and blue LEDs initially in the green vegetative cell period, and then using only red LEDs in the green resting cell period. Results showed that average biomass productivity of red and (red + blue) LEDs increased by 67.02% and 52.63%, respectively, compared to the control group. The red LEDs resulted in the desired cell concentration and extend the green stage, while blue LEDs or higher light intensities promoted cell division. This study also found that incremental light intensity could improve growth, and the modified initial nitrate contents or fed-batch culture could support longer period for seed cultivation.
This work further explored strategies to optimize green cell growth under red LED irradiation. By applying fractional factorial analysis, the significant factors were identified, then optimal combinations were analyzed using response surface method. Validation results showed that with the optimal conditions, significant improvements could be achieved. The maximum specific growth rate, average biomass productivity and duration of the green stage reached 0.65 d-1, 0.26 g L-1 d-1 and 21.07 d, respectively.
A parameterized light distribution model for green cell growth was also developed using the Gauss-Newton and bootstrap methods. The parameters of the model were estimated to be 118.79 ± 5.18 m-1 and 0.25 ± 0.04 g L-1, with 95% confidence intervals of (111.57, 129.79) and (0.20, 0.33), respectively. Validation results demonstrated that the established model was reliable and that it could accurately predict light intensity for indoor cultivation in the green stage.
Overall, findings from this dissertation study not only filled some technological gaps in lighting strategies for cultivating Haematococcus pluvialis in the green stage, but also demonstrated effectiveness of using statistics and modeling tools in algal research.
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Details
- Title
- EVALUATION AND OPTIMIZATION OF CULTIVATION CONDITIONS AND PARAMETERIZATION OF A LIGHT DISTRIBUTION MODEL FOR GREEN CELL GROWTH OF THE MICROALGAE: HAEMATOCOCCUS PLUVIALIS UNDER AUTOTROPHIC CONDITIONS
- Creators
- Xin Gao
- Contributors
- Shulin Chen (Advisor)Helmut Kirchhoff (Committee Member)Haijun Li (Committee Member)Sanja Roje (Committee Member)Shyam S Sablani (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Voiland College of Engineering and Architecture
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 118
- Identifiers
- 99900581633901842
- Language
- English
- Resource Type
- Dissertation