Del Río Esperanza, Acién F Gabriel, García-Malea M Carmen, Rivas Joaquín, Molina-Grima Emilio, Guerrero Miguel G
Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-Consejo Superior de Investigaciones Científicas, Centro de Investigaciones Científicas Isla de la Cartuja, Avda. Américo Vespucio, 49, 41092-Sevilla, Spain.
Biotechnol Bioeng. 2008 Jun 1;100(2):397-402. doi: 10.1002/bit.21770.
Continuous cultivation of Haematococcus pluvialis under moderate nitrogen limitation represents a straightforward strategy, alternative to the classical two-stage approach, for astaxanthin production by this microalga. Performance of the one-step system has now been validated for more than 40 combinations of dilution rate, nitrate concentration in the feed medium, and incident irradiance, steady state conditions being achieved and maintained in all instances. Specific nitrate input and average irradiance were decisive parameters in determining astaxanthin content of the biomass, as well as productivity of the system. The growth rate of the continuous photoautotrophic cultures was a hyperbolic function of average irradiance. As long as specific nitrate input was above the threshold value of 2.7 mmol/g day, cells performed green and astaxanthin was present at basal levels only. Below the threshold value, under moderate nitrogen limitation conditions, astaxanthin accumulated to reach cellular levels of up to 1.1% of the dry biomass. Increasing irradiance resulted in enhancement of astaxanthin accumulation when nitrogen input was limiting, but never under nitrogen sufficiency. Mean daily productivity values of 20.8 +/- 2.8 mg astaxanthin/L day (1.9 +/- 0.3 g dry biomass/L day) were consistently achieved for a specific nitrate input of about 0.8 mmol/g day and an average irradiance range of 77-110 microE/m(2) s. Models relating growth rate and astaxanthin accumulation with both average irradiance and specific nitrate input fitted accurately experimental data. Simulations provided support to the contention of achieving efficient production of the carotenoid through convenient adjustment of the determining parameters, and yielded productivity estimates for the one-step system higher than 60 mg astaxanthin/L day. The demonstrated capabilities of this production system, as well as its product quality, made it a real alternative to the current two-stage system for the production of astaxanthin-rich biomass.
在适度氮限制条件下对雨生红球藻进行连续培养，是一种简单直接的策略，可替代传统的两阶段方法来生产虾青素。目前，该一步法系统在超过40种稀释率、进料培养基中硝酸盐浓度和入射辐照度的组合下得到了验证，在所有情况下均能实现并维持稳态条件。特定硝酸盐输入量和平均辐照度是决定生物量中虾青素含量以及系统生产力的关键参数。连续光合自养培养物的生长速率是平均辐照度的双曲线函数。只要特定硝酸盐输入量高于2.7 mmol/g·天的阈值，细胞就呈绿色，虾青素仅以基础水平存在。低于该阈值，在适度氮限制条件下，虾青素积累至细胞水平，最高可达干生物量的1.1%。当氮输入受限但氮充足时，增加辐照度会导致虾青素积累增加。对于约0.8 mmol/g·天的特定硝酸盐输入量和77 - 110 μE/m²·s的平均辐照度范围，平均日生产力值始终达到20.8 ± 2.8 mg虾青素/升·天（1.9 ± 0.3 g干生物量/升·天）。将生长速率和虾青素积累与平均辐照度和特定硝酸盐输入量相关联的模型准确拟合了实验数据。模拟结果支持了通过方便地调整决定参数来有效生产类胡萝卜素的观点，并得出一步法系统的生产力估计值高于60 mg虾青素/升·天。该生产系统所展示的能力及其产品质量，使其成为当前生产富含虾青素生物量的两阶段系统的真正替代方案。
