基因工程改造微藻细胞赋予其可控自絮凝表型实现低成本沉降采收

Microalgae are efficient in photosynthesis converting carbon dioxide into biomass and tolerant to environmental stresses, making them suitable for large scale culture at low cost with open culture systems. When enriched with lipids or starch, microalgae can be used as feedstock for producing biofuels such as biodiesel by the transesterification reaction or other bio-based products through microbial fermentations. In addition, microalgae are useful in bioremediation applications for wastewater treatment. Therefore, they are significant for the sustainable development of economy, environment and society. However, microalgal cells are tiny, and large quantity of culture broth must be processed for biomass recovery due to extremely low cell density achieved under open culture conditions, which presents the biggest challenge for the culture of microalgae biomass at large scale for the purpose of biorefinery. Apparently, engineering microalgae with the self-flocculating phenotype for biomass recovery through sedimentation is a cost-effective strategy..In this project, the microalgae Chlorella vulgaris accumulating lipids and Scenedesmus obliquus for wastewater treatment are selected as model systems, and genetic manipulations will be applied to them by heterologous expression of the FLO gene isolated from the self-flocculating yeast Saccharomyces cerevisiae for the self-flocculating phenotype to facilitate the sedimentation of the genetically modified microalgal species. Furthermore, the impact of the self-flocculation on the growth of microalgal cells and accumulation of intracellular lipids will be investigated with an objective to optimizing the genetic transformation system. With the progress, the bottleneck associated with microalgae biomass recovery is expected to be addressed.

微藻光合效率高，抗污去污能力强，可以大规模低成本开放培养，获得油脂或淀粉含量高的生物质，用于生产生物柴油等生物能源产品或微生物发酵生产其他生物基产品，也可用于有机废水处理，对经济、环境和社会的可持续发展具有重要意义。然而微藻不仅细胞小，而且表面携带负电荷，特别是开放培养条件下藻细胞浓度极低等特点，使微藻采收成本居高不下，成为微藻生物质大规模加工利用的瓶颈。通过基因工程改造，赋予微藻自絮凝能力，实现自絮凝沉降采收，是最经济的策略。. 本项目以产油脂小球藻和抗污能力强适宜于异养处理有机废水斜生栅藻为研究对象，建立高效遗传转化体系，将酿酒酵母絮凝基因在微藻细胞中表达，赋予其自絮凝表型，进而研究微藻自絮凝对生长和油脂积累的影响，建立相应的调控策略，在不影响藻细胞生长和油脂积累条件下实现自絮凝沉降采收。取得的研究进展可以为微藻大规模培养低成本采收创新技术开发奠定科学和技术基础。

微藻光合效率高，抗污去污能力强，可以大规模低成本开放培养，获得油脂或淀粉含量高的生物质，用于生产生物柴油等生物能源产品或微生物发酵生产其他生物基产品，也可用于有机废水处理，对经济、环境和社会的可持续发展具有重要意义。然而微藻细胞小、表面携带负电荷以及开放培养条件下藻细胞浓度极低等特点使微藻采收成本居高不下，成为微藻生物质大规模加工利用的瓶颈。通过基因工程改造，赋予微藻自絮凝能力，实现自絮凝沉降采收，是最经济的策略。.本项目以在能源生产和污水处理中应用较为广泛的斜生栅藻作为研究对象，建立酵母絮凝基因转化微藻的技术平台，赋予其可调控的自絮凝表型，在不影响藻细胞生长和代谢产物积累的条件下，实现微藻的自絮凝沉降采收。项目的总体研究目标基本完成。取得的研究进展可以为微藻大规模培养低成本采收创新技术开发奠定科学和技术基础。