Schmid A, Kollmer A, Mathys R G, Witholt B
Institute of Biotechnology, ETH Hönggerberg, Zürich, Switzerland.
Extremophiles. 1998 Aug;2(3):249-56. doi: 10.1007/s007920050067.
Many pseudomonads and other bacteria can grow on aliphatic and aromatic hydrocarbons that occur in the environment. We are examining the potential of such organisms as biocatalysts for the oxidation of a variety of substituted aliphatic and aromatic compounds. To attain a high production rate of oxidation products via such biotransformations, we have focused on two-liquid phase culture systems. In these systems, cells are grown in liquid media consisting of an aqueous phase containing water-soluble growth substrates and droplets of a water-immicible organic solvent containing bioconversion substrates and products. For industrial applications of such two-liquid phase processes, several questions remain. What are the maximum rates at which apolar compounds can be transferred from the apolar phase to cells growing in the aqueous phase, i.e., what are the maximum space-time yields attainable in two-liquid phase fermentations under practical conditions? What does an efficient downstream processing of two-liquid phase medium involve? What safety regimes should be considered in working with flammable organic solvents? Can elevated pressure be used to increase oxygen transfer? Based on answers to these questions, we have recently developed a high-pressure, explosion-proof bioreactor system with Bioengineering AG (Wald, Switzerland), which will be installed in our pilot plant and used to explore two-liquid phase bioconversions at a pilot scale.
许多假单胞菌和其他细菌能够在环境中存在的脂肪族和芳香族碳氢化合物上生长。我们正在研究这类微生物作为生物催化剂对各种取代脂肪族和芳香族化合物进行氧化的潜力。为了通过此类生物转化获得高氧化产物产率，我们将重点放在双液相培养系统上。在这些系统中，细胞在由含有水溶性生长底物的水相和含有生物转化底物及产物的与水不混溶的有机溶剂液滴组成的液体培养基中生长。对于此类双液相过程的工业应用，仍存在几个问题。非极性化合物从非极性相转移到在水相中生长的细胞的最大速率是多少，即在实际条件下双液相发酵可达到的最大时空产率是多少？双液相培养基的高效下游加工涉及哪些内容？在使用易燃有机溶剂时应考虑哪些安全措施？能否使用高压来增加氧气传递？基于对这些问题的回答，我们最近与瑞士瓦尔德的生物工程股份公司共同开发了一种高压、防爆生物反应器系统，该系统将安装在我们的中试工厂中，用于中试规模地探索双液相生物转化。
