Hejazi M A, Wijffels R H
Food and Bioprocess Engineering Group, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Biomol Eng. 2003 Jul;20(4-6):171-5. doi: 10.1016/s1389-0344(03)00046-7.
Application of two-phase bioreactors is a useful technique for improvement of the productivity of fermentations. Fermentative extraction of the products in situ is performed in this technique. The effect of light intensity on the extraction of beta-carotene from Dunaliella salina, in the fermentative extraction, has been investigated. Three different average light exposures were applied: 1.5 x 10(-8) (low), 2.7 x 10(-8) (intermediate) and 4.5 x 10(-8) (high) micromol s(-1) per cell. Results show that beta-carotene content of the cells increases by increasing the light exposure. Increase in the beta-carotene content of the cells is not necessarily coupled with an increase in the volumetric production of beta-carotene. Final volumetric production is about the same for the three bioreactors. beta-Carotene extraction rate is enhanced by the increase in the light exposure. The results suggest that extraction rate is related to beta-carotene content of the cells and is not essentially related to the volumetric production of beta-carotene. Although the effectiveness of extraction with respect to the light input is comparable for all light intensities applied, increasing the light input per cell leads to a higher volumetric extraction rate. Moreover, extracted beta-carotene stays very pure even so the extraction increased by the increase of light intensity.
两相生物反应器的应用是提高发酵生产率的一项有用技术。该技术可原位进行产物的发酵提取。研究了光强对盐藻发酵提取β-胡萝卜素的影响。设置了三种不同的平均光照量：每细胞1.5×10⁻⁸（低）、2.7×10⁻⁸（中）和4.5×10⁻⁸（高）微摩尔每秒。结果表明，细胞中β-胡萝卜素含量随光照量增加而增加。细胞中β-胡萝卜素含量的增加不一定与β-胡萝卜素的体积产量增加相关。三个生物反应器的最终体积产量大致相同。β-胡萝卜素提取率随光照量增加而提高。结果表明，提取率与细胞中β-胡萝卜素含量有关，而与β-胡萝卜素的体积产量无本质关联。尽管在所施加的所有光强下，相对于光输入的提取效率相当，但每细胞光输入的增加会导致更高的体积提取率。此外，即使提取量因光强增加而增加，提取出的β-胡萝卜素仍保持非常纯净。
