Overmans Sebastian, Lauersen Kyle J
Bioengineering Program, Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Kingdom of Saudi Arabia
RSC Adv. 2022 Jun 6;12(26):16632-16639. doi: 10.1039/d2ra01112c. eCollection 2022 Jun 1.
Microbial production of heterologous metabolites is now a mature technology in many host organisms, opening new avenues for green production processes of specialty chemicals. At lab scale, petroleum-based hydrophobic bio-compatible solvents like dodecane can be used as a second phase on top of microbial cultures to act as a physical sink for heterologous hydrocarbon products like isoprenoids. However, this approach has significant drawbacks at scale due to the difficulty of handling solvents and their potential contamination with unwanted byproducts of their manufacture. We discovered that synthetic perfluorocarbon liquids (FCs), commonly used for heat transfer, can also act as physical sinks for microbially produced isoprenoid compounds. FCs are stable, inert, and are amenable to direct liquid-liquid extraction with alcohols for rapid product isolation. These liquids are more dense than water and form a lower phase to microbial cultures rather than an upper phase as with other solvents. Their ability to form an under-layer or 'underlay' also enables the cultivation of microbes directly at the FC-culture medium interface gravity settling, which could open their application for filamentous or mat-forming organisms. We present comparisons of the isoprenoid extraction potential of three commercial FCs: FC-3283, FC-40, and FC-770 with engineered green microalga cultures producing patchoulol, taxadiene, casbene, or 13(+) manoyl oxide. We demonstrate that FCs are promising alternatives to traditional solvents and open new avenues in bio-process design for microbial heterologous metabolite milking.
微生物生产异源代谢产物如今在许多宿主生物体中已成为一项成熟技术，为特种化学品的绿色生产工艺开辟了新途径。在实验室规模下，基于石油的疏水性生物相容性溶剂（如十二烷）可作为微生物培养物上方的第二相，充当异源烃类产物（如类异戊二烯）的物理汇。然而，由于处理溶剂存在困难以及它们可能被其制造过程中产生的不需要的副产物污染，这种方法在规模化时存在重大缺陷。我们发现，常用于传热的合成全氟化碳液体（FCs）也可作为微生物生产的类异戊二烯化合物的物理汇。FCs稳定、惰性，并且适合与醇类进行直接液 - 液萃取以快速分离产物。这些液体比水密度大，在微生物培养物下方形成下层，而不像其他溶剂那样形成上层。它们形成下层或“底层”的能力还使得能够在FC - 培养基界面通过重力沉降直接培养微生物，这可能为丝状或形成菌毯的生物体开辟其应用前景。我们比较了三种商业FCs（FC - 3283、FC - 40和FC - 770）对工程化绿色微藻培养物生产广藿香醇、紫杉二烯、蓖麻二烯酸或13(+) - 异曼oyl氧化物的类异戊二烯萃取潜力。我们证明FCs是传统溶剂的有前景的替代品，并为微生物异源代谢产物提取的生物工艺设计开辟了新途径。
