Targeted saturated fatty acids synthesis by microbial biohydrogenation and its superior extraction from microalgae biomass through selective fermentation

The information was adapted from the NSF project abstract.Microalgae are single-celled photosynthetic organisms that grow on atmospheric carbon dioxide, sunlight, and dissolved mineral nutrients. Under the proper conditions, microalgae also produce fatty acids stored as lipids, which can be readily converted to biofuel such as biodiesel. This proposed research will explore a new process called selective fermentation to address two major roadblocks facing the continued commercial development algal biofuel production processes: safe and efficient extraction of the lipids, and beneficial use of the non-lipid biomass. Selective fermentation involves the conversion of carbohydrate and protein fractions of microalgae biomass to short-chain fatty acids while leaving the lipid fraction intact and more easily available for extraction by non-toxic solvents. This research has the potential to improve biofuel yield from algal biomass and reduce waste, thereby increasing efficiency and promoting sustainability of algal biofuel production processes.The production of liquid transportation fuels from microalgae faces many challenges, including the safe and efficient extraction of lipids, and in the beneficial use of the non-lipid components in the biomass. This project will study the potential of selective fermentation to simultaneously address these two challenges. In the proposed selective fermentation process, the carbohydrate and protein fractions of the microalgal biomass are fermented to short-chain fatty acids, while the existing lipid fraction is conserved in a form that is more readily extracted from the non-fermented biomass. To increase the rate and extent of carbohydrate and protein fermentation, the selective fermentation process will be carried out in the anode chamber of a microbial electrolysis cell (MEC), which produces hydrogen gas at the cathode, consumes the fermentation products, and promotes bio-hydrogenation of unsaturated fatty acids to saturated fatty acids with higher fuel quality.本信息改编自美国国家科学基金会（National Science Foundation, NSF）项目摘要。微藻（microalgae）是一类单细胞光合生物，可利用大气二氧化碳、阳光以及溶解态矿质营养进行生长繁殖。在适宜条件下，微藻还会合成以脂质形式储存的脂肪酸，这类物质可轻松转化为生物柴油等生物燃料。本项拟开展研究将探索一种名为选择性发酵（selective fermentation）的新工艺，以解决藻类生物燃料生产工艺持续商业化面临的两大核心障碍：脂质的安全高效提取，以及非脂质生物质的资源化利用。选择性发酵工艺可将微藻生物质中的碳水化合物与蛋白质组分转化为短链脂肪酸，同时保留脂质组分的完整性，使其更易于通过无毒溶剂进行提取。本研究有望提升藻类生物质的生物燃料产率并减少废弃物产生，进而提高藻类生物燃料生产的效率，推动其可持续发展。利用微藻生产液态交通燃料面临诸多挑战，其中包括脂质的安全高效提取，以及生物质中非脂质组分的资源化利用。本项目将研究选择性发酵工艺解决这两大难题的应用潜力。在拟采用的选择性发酵工艺中，微藻生物质的碳水化合物与蛋白质组分将被发酵转化为短链脂肪酸，而原有脂质组分则以更易于从未发酵生物质中提取的形式得以保留。为提高碳水化合物与蛋白质的发酵速率和转化程度，本工艺将在微生物电解池（microbial electrolysis cell, MEC）的阳极室中开展：该装置可在阴极产生氢气，同时消耗发酵产物，并促进不饱和脂肪酸的生物加氢反应，将其转化为燃料品质更高的饱和脂肪酸。