Wageningen University, Bioprocess Engineering, P.O. Box 8129, 6700 EV, Wageningen, The Netherlands.
Enzyme Microb Technol. 2011 Mar 7;48(3):253-9. doi: 10.1016/j.enzmictec.2010.11.005. Epub 2010 Nov 18.
During the in situ extraction of β-carotene from Dunaliella salina, the causal relationship between carotenoid extraction and cell death indicated that cell growth and cell death should be at equilibrium for a continuous in situ extraction process. In a flat-panel photobioreactor that was operated as a turbidostat cell numbers of stressed cells were kept constant while attaining a continuous well-defined light-stress. In this way it was possible to study the balance between cell growth and cell death and determine whether both could be increased to reach higher volumetric productivities of carotenoids. In the two-phase system a volumetric productivity of 8.3 mg β-carotene L(RV)(-1)d(-1) was obtained. In situ extraction contributed only partly to this productivity. The major part came from net production of carotenoid-rich biomass, due to a high growth rate of the cells and subsequent dilution of the reactor. To reach equilibrium between cell growth and cell death, sparging rates of dodecane could have been increased. However, already at the applied sparging rate of 286 L(dod)L(RV)(-1)min(-1) emulsion formation of the dodecane in the aqueous phase appeared. In a turbidostat without in situ extraction a volumetric productivity of 13.5 mg β-caroteneL(RV)(-1)d(-1) was reached, solely based on the continuous production of carotenoid-rich biomass.
在从盐生杜氏藻原位提取 β-胡萝卜素的过程中，类胡萝卜素提取与细胞死亡之间的因果关系表明，对于连续的原位提取过程，细胞生长和细胞死亡应该达到平衡。在作为恒浊器运行的平板光生物反应器中，通过保持受胁迫细胞的数量不变，同时达到连续的明确的光胁迫，可以研究细胞生长和细胞死亡之间的平衡，并确定两者是否都可以增加以达到更高的类胡萝卜素体积产率。在两相体系中，获得了 8.3mgβ-胡萝卜素 L(RV)(-1)d(-1)的体积产率。原位提取仅对这一产率有部分贡献。主要部分来自富含类胡萝卜素的生物量的净生产，这是由于细胞的高生长速率以及随后对反应器的稀释。为了达到细胞生长和细胞死亡之间的平衡，可以增加十二烷的通气速率。然而，在应用的 286L(dod)L(RV)(-1)min(-1)的通气速率下，十二烷在水相中的乳化已经出现。在没有原位提取的恒浊器中，仅基于富含类胡萝卜素的生物量的连续生产，就达到了 13.5mgβ-胡萝卜素 L(RV)(-1)d(-1)的体积产率。
