Biochemical System Analysis of Lutein Production by Heterotrophic Chlorella pyrenoidosa in a Fermentor 

Zheng-Yun Wu^1,2, Chun-Bo Qu² and Xian-Ming Shi²*

¹Department of Food Engineering, Sichuan University, CN-610065 Chengdu, PR China
²Department of Food Science and Engineering and Bor Luh Food Safety Center, Shanghai Jiao Tong University, CN-200240 Shanghai, PR China

Article history:
Received September 10, 2008
Accepted March 25, 2009

Key words:
Chlorella pyrenoidosa, lutein, heterotrophic cultivation, biochemical system analysis, modelling

Summary:
Chlorella is a promising alternative source of lutein, as it can be cultivated heterotrophically with high efficiency. In this study, the carotenoids in Chlorella pyrenoidosa heterotrophically cultivated in a 19-litre fermentor have been analyzed and determined by using HPLC and HPLC-MS. A biochemical system theory (BST) model was developed for understanding the regulatory features of carotenoid metabolism during the batch cultivation. Factors that influence lutein production by C. pyrenoidosa were discussed based on the model. It shows that low flux for lycopene formation is the major bottleneck for lutein production, while by-product syntheses and inhibitions affect the cellular lutein content much less. However, with further increase of the cellular lutein content, the inhibition on lycopene formation by lutein may become a limiting factor. Although speculative, these results may provide useful information for further elucidation of the regulatory mechanisms of carotenoid biosynthesis in Chlorella and modifying its metabolic network to enhance lutein production.

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