Department of Chemical Sciences, University of Naples Federico II, via Cinthia 4, 80126 Naples, Italy.
Centre of Marine Sciences, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
Int J Mol Sci. 2024 Sep 24;25(19):10238. doi: 10.3390/ijms251910238.
Downstream costs represent one of the main obstacles to enabling microalgae to become widespread. The development of an economical, easily scaled-up strategy could reduce the overall process costs. Here, different flocculants were tested on different microalgae strains and a cyanobacterium. The results indicate that flocculation could be an alternative to centrifugation, as CaCl induced a complete flocculation of green and red marine strains (96 ± 4% and 87.0 ± 0.5%, respectively), whereas Chitosan was the only agent able to induce flocculation on the cyanobacterium (46 ± 1%). As for the thermoacidophilic red microalga, 100% flocculation was achieved only by increasing the pH. Carotenoids were extracted from the flocculated biomass, and the strategy improved with the use of the wet biomass. The results indicate that flocculation does not affect carotenoid yield, which is at least the same than that obtained upon centrifugation and extraction from the wet biomass. Then, for the first time, the biological activity of the extracts obtained from the flocculated biomasses was evaluated. The results indicate that only the green microalga extract shows increased antioxidant activity. In conclusion, this work highlights that a general downstream procedure cannot be developed for microalgae strains but should be rationally tailored.
下游成本是使微藻广泛应用的主要障碍之一。开发经济、易于规模化的策略可以降低整个过程的成本。在这里，不同的絮凝剂被测试于不同的微藻菌株和一种蓝藻。结果表明，絮凝可以替代离心，因为 CaCl 诱导绿色和红色海洋菌株（分别为 96±4%和 87.0±0.5%）完全絮凝，而壳聚糖是唯一能够诱导蓝藻絮凝的试剂（46±1%）。对于嗜热嗜酸的红色微藻，只有通过提高 pH 值才能实现 100%的絮凝。类胡萝卜素从絮凝的生物质中提取，该策略通过使用湿生物质得到了改善。结果表明，絮凝不会影响类胡萝卜素的产量，至少与从湿生物质中离心和提取得到的产量相同。然后，首次评估了从絮凝生物质中获得的提取物的生物活性。结果表明，只有绿色微藻提取物显示出增强的抗氧化活性。总之，这项工作强调，不能为微藻菌株开发通用的下游程序，而应合理定制。
