Benvenuti Giulia, Bosma Rouke, Ji Fang, Lamers Packo, Barbosa Maria J, Wijffels René H
Bioprocess Engineering, AlgaePARC, Wageningen University, P.O. Box 16, 6700 AA Wageningen, The Netherlands.
Biomass Engineering Center, China Agricultural University, P.O. Box 50, Beijing, 100083 China.
J Appl Phycol. 2016;28(6):3167-3177. doi: 10.1007/s10811-016-0897-1. Epub 2016 Jul 7.
Microalgal triglycerides (TAGs) represent a sustainable feedstock for food, chemical and biofuel industries. The operational strategy (batch, semi-continuous, continuous cultivations) has an impact on the TAG productivity. In this study, semi-continuous (i.e. with fixed harvesting frequency) and batch cultivations were compared on TAG production both at lab-scale and in outdoor cultivations. At lab-scale, the semi-continuous TAG productivity was highest for a cycle time of 2 days (SC1; 0.21 g L day) and similar to the maximum obtained with the batch (optimal harvest time; 0.23 g L day). Although TAG content was lower for SC1 (22 %) than for the batch (35 %), higher biomass productivities were obtained with SC1. Outdoors, semi-continuous cultivations were subjected to a lower degree of stress (i.e. higher amount of nitrogen present in the system relative to the given irradiance) compared to lab-scale. This yielded low and similar TAG contents (10-13 %) in the different semi-continuous runs that were outdone by the batch on both TAG content (15-25 %) and productivity (batch, 0.97-2.46 g m day; semi-continuous, 0.35-0.85 g m day). The lab-scale experiments showed that semi-continuous strategies, besides leading to similar TAG productivities compared to the batch, could make TAG production cost effective by valorising also non-TAG compounds. However, optimization of outdoor semi-continuous cultivations is still required. For instance, the nitrogen supply and the harvest frequency should be adjusted on the total irradiance. Additionally, future research should focus on recovery metabolism upon nitrogen resupply.
微藻甘油三酯（TAGs）是食品、化工和生物燃料行业可持续的原料。操作策略（分批、半连续、连续培养）会影响TAG的生产率。在本研究中，在实验室规模和室外培养条件下，比较了半连续（即固定收获频率）培养和分批培养对TAG产量的影响。在实验室规模下，半连续TAG生产率在2天的循环时间（SC1；0.21 g L⁻¹天⁻¹）时最高，与分批培养（最佳收获时间；0.23 g L⁻¹天⁻¹）获得的最大值相似。虽然SC1的TAG含量（22%）低于分批培养（35%），但SC1获得了更高的生物质生产率。在室外，与实验室规模相比，半连续培养受到的胁迫程度较低（即相对于给定辐照度，系统中存在的氮量较高）。这导致不同半连续培养批次中的TAG含量较低且相似（10 - 13%），在TAG含量（15 - 25%）和生产率（分批培养，0.97 - 2.46 g m⁻²天⁻¹；半连续培养，0.35 - 0.85 g m⁻²天⁻¹）方面均低于分批培养。实验室规模的实验表明，半连续策略除了能产生与分批培养相似的TAG生产率外，还可以通过利用非TAG化合物使TAG生产成本效益更高。然而，仍需要优化室外半连续培养。例如，应根据总辐照度调整氮供应和收获频率。此外，未来的研究应关注氮再供应后的恢复代谢。
