Banerjee Shivali, Dien Bruce S, Singh Vijay
Department of Agricultural and Biological Engineering, University of Illinois Urbana-Champaign, 1304 W. Pennsylvania Avenue, Urbana, IL, 61801, USA.
DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
Biotechnol Biofuels Bioprod. 2024 Aug 16;17(1):114. doi: 10.1186/s13068-024-02561-x.
Lipids produced using oleaginous yeast cells are an emerging feedstock to manufacture commercially valuable oleochemicals ranging from pharmaceuticals to lipid-derived biofuels. Production of biofuels using oleaginous yeast is a multistep procedure that requires yeast cultivation and harvesting, lipid recovery, and conversion of the lipids to biofuels. The quantitative recovery of the total intracellular lipid from the yeast cells is a critical step during the development of a bioprocess. Their rigid cell walls often make them resistant to lysis. The existing methods include mechanical, chemical, biological and thermochemical lysis of yeast cell walls followed by solvent extraction. In this study, an aqueous thermal pretreatment was explored as a method for lysing the cell wall of the oleaginous yeast Rhodotorula toruloides for lipid recovery.
Hydrothermal pretreatment for 60 min at 121 °C with a dry cell weight of 7% (w/v) in the yeast slurry led to a recovery of 84.6 ± 3.2% (w/w) of the total lipids when extracted with organic solvents. The conventional sonication and acid-assisted thermal cell lysis led to a lipid recovery yield of 99.8 ± 0.03% (w/w) and 109.5 ± 1.9% (w/w), respectively. The fatty acid profiles of the hydrothermally pretreated cells and freeze-dried control were similar, suggesting that the thermal lysis of the cells did not degrade the lipids.
This work demonstrates that hydrothermal pretreatment of yeast cell slurry at 121 °C for 60 min is a robust and sustainable method for cell conditioning to extract intracellular microbial lipids for biofuel production and provides a baseline for further scale-up and process integration.
利用产油酵母细胞生产的脂质是一种新兴原料，可用于制造从药物到脂质衍生生物燃料等具有商业价值的油脂化学品。使用产油酵母生产生物燃料是一个多步骤过程，需要酵母培养和收获、脂质回收以及将脂质转化为生物燃料。从酵母细胞中定量回收总细胞内脂质是生物工艺开发过程中的关键步骤。它们坚硬的细胞壁通常使它们具有抗裂解性。现有方法包括对酵母细胞壁进行机械、化学、生物和热化学裂解，然后进行溶剂萃取。在本研究中，探索了水热预处理作为一种裂解产油酵母红酵母细胞壁以回收脂质的方法。
在酵母浆液中干重为7%（w/v）的条件下，于121℃进行60分钟的水热预处理，用有机溶剂萃取时，总脂质回收率为84.6±3.2%（w/w）。传统的超声处理和酸辅助热细胞裂解的脂质回收率分别为99.8±0.03%（w/w）和109.5±1.9%（w/w）。水热预处理细胞和冷冻干燥对照的脂肪酸谱相似，表明细胞的热裂解没有使脂质降解。
这项工作表明，在121℃对酵母细胞浆液进行60分钟的水热预处理是一种用于细胞预处理以提取细胞内微生物脂质用于生物燃料生产的稳健且可持续的方法，并为进一步扩大规模和工艺整合提供了基线。
