Padhi Diptymayee, Nayak Manoranjan
Biorefinery and Bioenergy Research Laboratory, Amity Institute of Biotechnology, Amity University, Noida, 201313, Uttar Pradesh, India.
Biorefinery and Bioenergy Research Laboratory, Amity Institute of Biotechnology, Amity University, Noida, 201313, Uttar Pradesh, India.
Chemosphere. 2025 Sep;385:144529. doi: 10.1016/j.chemosphere.2025.144529. Epub 2025 Jun 18.
Microalgae growth and lipid production via two-stage cultivation is challenging on a large scale due to the high energy demand for transferring biomass from the first to the second stage. To address this, the present study implements a continuous two-stage (CTS) cultivation strategy using Chlorella sp. BRE5 to enhance lipid productivity without compromising biomass growth. Shake flask experiments were initially conducted to evaluate the effects of varying phosphorus (P) doses (100 %, 250 %, 500 %, 750 %, and 1000 %) under four sets of nitrogen (N) and sulphur (S) supplementation conditions during the second stage of CTS cultivation: (i) N0-S0, (ii) N0-S100, (iii) N100-S0, and (iv) N100-S100. Results from these experiments guided a comparative photobioreactor (PBR) study, which revealed that the highest biomass productivity of 300.6 mg L d was achieved under PBR (N0-S100-P250) conditions, i.e., N deficiency with S (100 %) re-supplementation and surplus P (250 %) on the 8th day of the second stage of CTS. Under these conditions, lipid productivity was 2.74 times higher than that of the PBR (Control). The fatty acid profile composed of C16/C18, showing more than 88 % of the total fatty acids, and the estimated biodiesel properties meet international standards (EN-14214 and ASTM D-6751). These findings highlight that luxury P supply, when applied in the second stage of CTS cultivation, promoted lipid productivity in Chlorella sp. BRE5 offers a promising approach for enhanced biodiesel production.
由于将生物质从第一阶段转移到第二阶段需要高能量需求，通过两阶段培养实现微藻生长和脂质生产在大规模生产中具有挑战性。为了解决这个问题，本研究采用小球藻BRE5实施了一种连续两阶段（CTS）培养策略，以提高脂质生产力而不影响生物质生长。最初进行了摇瓶实验，以评估在CTS培养第二阶段的四组氮（N）和硫（S）补充条件下，不同磷（P）剂量（100%、250%、500%、750%和1000%）的影响：（i）N0-S0，（ii）N0-S100，（iii）N100-S0，和（iv）N100-S100。这些实验结果指导了一项比较光生物反应器（PBR）研究，该研究表明，在PBR（N0-S100-P250）条件下，即在CTS培养第二阶段的第8天，氮缺乏且硫（100%）重新补充以及磷过剩（250%）的情况下，实现了最高生物质生产力300.6 mg L d。在这些条件下，脂质生产力比PBR（对照）高2.74倍。由C16/C18组成的脂肪酸谱显示，占总脂肪酸的88%以上，并且估计的生物柴油特性符合国际标准（EN-14214和ASTM D-6751）。这些发现突出表明，在CTS培养的第二阶段应用奢侈磷供应可提高小球藻BRE5的脂质生产力，为提高生物柴油产量提供了一种有前景的方法。
