胡群菊1,2，向文洲1，杨芳芳1,2，贾其坤1,2，吴华莲1，李涛1，何慧1，范杰伟1
(1中国科学院南海海洋研究所热带海洋生物资源可利用重点实验室，广东省海洋药物重点实验室，广州 510301；
2中国科学院大学，北京 100049)

摘要: 针对微藻采收成本高的难题，以一株微拟球藻（Nannochloropsis sp.）为实验材料，采用响应面法优化该藻株的高pH沉降采收技术，并初步评估其培养基的循环利用。结果显示，藻株培养液的细胞密度、沉降pH及处理时间3种因素对其采收效率（BRR）具有显著影响。预测最优采收参数为：藻细胞光密度OD750=2.08；沉降pH=12.20；处理时间 12 h，预测BRR为98.97%，验证实验实测BRR为98.31%。采收藻细胞后的上清液经过滤、pH调整及营养盐补充后，探究高pH采收后的培养基上清液的循环利用。与新鲜培养基相比，高pH采收回收培养基中的藻细胞生长和油脂含量有小幅度的降低，但总脂分级特性及脂肪酸组成无显著差异。该藻株的高pH采收及其培养基的回收利用方法具有可行性。
 

关键词：微拟球藻；高pH采收； 响应面法；培养基回收；生物柴油；EPA
 

Response surface optimization of flocculating Nannochloropsis sp. by pH increasing and reusing of flocculated medium
HU Qunju1,2, XIANG Wenzhou1, YANG Fangfang1,2, JIA Qikun1,2, WU Hualian1, LI Tao1, HE Hui 1, FAN Jiewei1
(1 Key Laboratory of Tropical Marine Bio-resources and Ecology, GuangDong Key Laboratory of Marine Materia Medica,
South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;
2 University of Chinese Academy of Sciences,Beijing 100049, China)

Abstract: High-cost harvesting technology is a limitation for industrial cultivation of microglgae. This report deals with the optimization of the high-pH-induced flocculation of a strain of Nannochloropsis sp. using the response surface methodology (RSM),with which a three-variable, three-level experiment Box–Behnken design (BBD) was developed to examine the effect of initial microalgal cell density (OD750), pH value and treating time on harvesting efficiency (biomass recovery rate, BRR) of the strain. The results showed that all the three factors significantly influenced the BRR, and the optimum flocculation parameters were as follows: OD750: 2.08, flocculating pH: 12.20, and treatment time: 12 h. Under the optimal condition, the value of BRR attained 98.31%, agreed well with the predicted value (98.97%). The feasibility of reusing the culture medium after high PH harvesting was further studied after the harvested supernatant treated with pH neutralization and nutrients supplementation. The results indicated that compared with the fresh medium, the medium made with high-pH harvesting supernatant resulted in a slight decrease in growth yield and lipid content, and no obvious changes in lipid distribution and fatty acid profiles, illustrating that reuse of culture medium after high pH-harvesting was acceptable for Nannochloropsis sp. production.
 

Key words: Nannochloropsis sp.; high pH harvesting; response surface methodology; reuse of culture medium; biodiesel; EPA