Faculty of Life Sciences and Technology, Kunming University of Science and Technology, Kunming 650500, China.
Faculty of Life Sciences and Technology, Kunming University of Science and Technology, Kunming 650500, China.
Sci Total Environ. 2022 Nov 15;847:157655. doi: 10.1016/j.scitotenv.2022.157655. Epub 2022 Jul 28.
Microalgae harvest and lipid accumulation were important factors influencing commercialized development of microalgae biodiesel. Spontaneous flocculation was an ideal method in microalgae harvest, but few rich lipid microalgae could be harvested by spontaneous flocculation. Rich lipid alga Heveochlorella sp. Yu has a characteristic of spontaneous flocculation to be harvested. Heveochlorella sp. Yu has high lipid productivity (105.24 mg L d) and fine spontaneous flocculation efficiency (82.93 %, 2 h) on early stationary phase (day 9). The polysaccharides consisting of glucose, mannose, galactose, rhamnose and fructose (8.67:4.90:3.27:2.16:1) in loose-bound extracellular polymeric substance (LB-EPS) might make great contribution in microalgae flocculation. Meanwhile, the zeta potential close to zero was also beneficial to microalgae flocculation. Besides, the adhesion free energy related with cells adhesion was detected by thermomechanical analysis. Afterward, Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory was utilized to quantitatively evaluate short-range interactions involved in the spontaneous aggregation among cells. Collectively, biophysical analyses indicated that content and composition of EPS, Zeta potential, thermodynamic parameter and total interaction based on XDLVO theory were closely connected with spontaneous flocculation in microalga Yu. Our study provided a harvest-simplified process of rich microalgae, which proposes a new idea for commercial development of microalgae biodiesel.
微藻的收获和脂质积累是影响微藻生物柴油商业化发展的重要因素。自然絮凝是微藻收获的一种理想方法，但很少有富含脂质的微藻可以通过自然絮凝收获。富含脂质的藻类羽藻属 Yu 具有自发絮凝的特点，可以被收获。羽藻属 Yu 在早期静止期（第 9 天）具有较高的产脂率（105.24mgLd）和良好的自发絮凝效率（82.93%，2h）。松散结合胞外聚合物（LB-EPS）中的多糖由葡萄糖、甘露糖、半乳糖、鼠李糖和果糖组成（8.67:4.90:3.27:2.16:1），可能对微藻絮凝有很大贡献。同时，接近零的zeta 电位也有利于微藻絮凝。此外，通过热机械分析检测了与细胞附着相关的无附着自由能。之后，利用扩展的 Derjaguin-Landau-Verwey-Overbeek（XDLVO）理论定量评估了细胞间自发聚集涉及的短程相互作用。总的来说，生物物理分析表明，EPS 的含量和组成、Zeta 电位、热力学参数和基于 XDLVO 理论的总相互作用与 Yu 微藻的自发絮凝密切相关。我们的研究提供了一种简化富含微藻收获的过程，为微藻生物柴油的商业化发展提出了新的思路。
