Abstract: Spirulina platensis (S. platensis) and its derivative products, have garnered considerable attention in the realms of food and biomedicine due to their high nutritional content. However, during the cultivation of S. platensis, copious amounts of water are required for both cell growth and nutrient suspension, leading to high water usage, increased costs, extensive nutrient waste, and substantial growth inhibition during the recycling process. This study aimed to assess the effectiveness of treating culture solution of S. platensis using four methods (0.45 μm filter membrane, 10 kDa ultrafiltration membrane, macroporous resin S-8, and activated carbon), evaluate the changes of growth and nutrient compositions of S. platensis after five recycles of culture solution, and identify the characteristics of extracellular inhibition and its constituents. The results showed that the circulation culture of Spirulina could greatly reduce the water consumption and culture cost, and improve the yield and quality of Spirulina. The culture solution pretreatment of S. platensis could effectively reduce the inhibition effect of extracellular organic matter, the negative effects can be effectively reduced, so that there was almost no difference between the microalgae obtained from the reused medium and the fresh medium and the order of treatment effects were 10 kDa ultrafiltration membrane>macroporous resin S-8>activated carbon>0.45 μm filter membrane. After five recycles of culture solution, the cell weight of S. platensis in the 10 kDa ultrafiltration membrane treatment group decreased only 5.9%, and that of the 0.45 μm filter membrane treatment group significantly decreased about 22% (p<0.05), but its intracellular polysaccharide content increased 217% due to the coercive effect of cell metabolism. In addition, the extracellular inhibitors in the culture solution were mainly extracellular polysaccharide, consisting of monosaccharides such as fucose (19.98%), rhamnose (15.61%), and glucose (14.75%). Therefore, this research holds significant implications for enabling sustainable, large-scale spirulina cultivation via the recycling of spirulina culture fluid. In addition, it contributes to nutrient accumulation, cost reduction, and decreased usage of nutrient salts.

Key words: Spirulina platensis, Recycling, ultrafiltration, Phycocyanin, extracellular polysaccharides

摘要： 针对螺旋藻培养耗水量大、成本较高、营养元素浪费严重且其培养液循环利用过程中生长受到严重抑制等问题。本工作采用0.45 μm滤膜、10 kDa超滤膜、大孔树脂S-8和活性炭处理螺旋藻培养液，评估处理后的培养液循环利用5次后，螺旋藻的生长及营养成分含量变化，并分析鉴定胞外抑制的组成成分。结果表明，螺旋藻培养液的处理可有效降低胞外有机物的抑制效果，其处理效果顺序为10 kDa超滤膜>大孔树脂S-8>活性炭>0.45 μm滤膜。培养液循环利用5次后，10 kDa超滤膜处理组的螺旋藻细胞干重仅下降5.9%，而0.45 μm滤膜处理组的细胞干重显著降低22% (p<0.05)，且由于细胞代谢的胁迫作用，其胞内多糖含量却增加了217%。此外，培养液中的胞外抑制物主要是由岩藻糖(19.98%)、鼠李糖(15.61%)和葡萄糖(14.75%)等单糖组成的多糖类有机物。

关键词: 螺旋藻, 循环利用, 超滤, 藻蓝蛋白, 胞外多糖