A structured approach to design and operation of biotransformation processes

A structured approach to design and operation of biotransformation (bioconversion) processes, based on previous case studies, has been developed. This requires knowledge of the key characteristics of a biotransformation which determine the constraints on process selection. The approach is illustrated for five biotransformations, two enzymic and three microbial. Some generic problems such as low water solubility and volatility of reactants, reactant and product toxicity have been identified. The microbial oxidations of toluene and fluorobenzene to toluene cis-glycol and fluorocatechol respectively by Pseudomonas putida have been used to illustrate how these constraints may be overcome by addition of tetradecane as a second liquid phase, use of a membrane oxygenator and introduction of in situ product removal.