外加粗甘油的污泥脱水液培养微藻体系的油脂积累强化机制解析

Cultivation of oil rich microalgae in centrate wastewater with crude glycerol addition, is in accord with the low carbon cycle development concept of bio-energy production and waste reuse. The lipid accumulation would be strengthened by the optimization of nutritional conditions and cultivation methods. However, the degradation of carbon and nitrogen, biosynthesis and degradation path of starch and lipid are not elucidated in the system of centrate wastewater with crude glycerol addition. Which is unfavorable for the establishment of process control strategy and the promotion of practical application of lipid accumulation in wastewater culture microalgae. Based on the preliminary research, the synergic relationship among the temporal variation of microalgae and bacteria abundance, carbon and nitrogen conversion, bioavailability would be analyzed in the project by metagenomics with high-throughput sequencing and flow cytometer, the characteristics and change rules of carbon and nitrogen. In order to determine the key metabolites and key regulatory factors of lipid accumulation and microalgae growth, the related metabolic pathways and their interaction between microalgae fixation glycerol and lipid synthesis would be analyzed by metabonomics and proteomics. This study will provide a scientific basis for establishment new and efficient wastewater treatment coupling with low cost of bio-oil production mode.

污泥脱水液-粗甘油培养富油微藻，符合生物能源生产和废物再利用的低碳循环发展理念。通过营养条件和培养方式的优化，强化培养体系的油脂积累。然而，补加粗甘油的污泥脱水液培养体系中碳氮的降解、淀粉与油脂的生物合成与降解路径尚不清楚，不利于废水培养微藻积累油脂过程调控策略的建立及实际应用的推进。本项目结合前期研究基础，拟借助高通量测序的宏基因组学和流式细胞仪，结合碳和氮的存在特征及变化规律，解析外加粗甘油时微藻、细菌丰度的时序性变化与碳氮转化、生物利用的协同关系；并利用代谢组学和蛋白组学分析方法，解析微藻甘油固定、油脂合成等相关代谢路径与其交互关系，以探究在粗甘油和污泥脱水液环境下微藻油脂积累与细胞生长的关键代谢物以及关键调控因子。为建立新型、高效的废水处理耦合低成本的生物油脂生产模式提供科学基础。

污泥脱水液-粗甘油培养富油微藻，符合生物能源生产和废物再利用的低碳循环发展理念。本项目通过营养条件和培养方式优化，强化培养体系油脂积累。设置藻菌共培养、小球藻单独培养、自生菌三个体系，考察藻菌生物量、代谢物、CO2和O2、以及细菌群落种类和丰度等变化，浅析藻菌共生机制。研究结果表明污泥脱水液中外加1.0~2.0 g/L的粗甘油、0.25 mg/L萘乙酸浓度、20 g/L NaCl胁迫处理48 h，均可获得更高油脂含量和油脂产量。胁迫培养后，藻细胞体积以及细胞内油滴数量和体积增加，淀粉颗粒减少，油滴存在融合现象，表明胁迫条件对油脂积累有强化作用。普通小球藻产出油脂的主要成分为C16~C22类脂肪酸。在MPBR中利用添加粗甘油的污泥脱水液对普通小球藻进行半连续分段培养，可提高普通小球藻的生物量产率，提升油脂积累水平，并去除大部分营养盐。藻菌共培养能够提高对污水中碳、氮、磷的利用率。藻菌共存体系存在CO2与O2的交换。胞外聚合物检测结果表明小球藻与自生菌均分泌蛋白质和多糖，扫描电镜发现藻菌之间在胞外聚合物粘连下成簇生长。高通量测序结果表明可与小球藻共生的优势菌属为Pseudomonas、Alicycliphilus、Gemmobacter、Flavobacterium。添加粗甘油后污泥脱水液中细菌对小球藻生长有促进作用。添加粗甘油后水样中的优势菌门为Proteobacteria，添加2 g/L与5 g/L粗甘油后Proteobacteria的丰度分别为87.5%、92.6%。为进一步探究藻菌关系提供基础。也为废水处理耦合低成本的生物油脂生产模式提供参考。