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 microblal oxidations of toluene and fluorobenzene to toluenecis-glycol and fluorocatechol respectively byPseudomonas 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 ofin situ product removal.     

The conversion of benzyl penicillin to 6-aminopenicillanic acid using an insoluble derivative of penicillin amidase

Penicillin amidase was extracted from Escherichia coli ATCC 9637, grown on phenylacetic, acid and glutamate, and purified by fractional ion with streptomycin sulphate, ammonium sulphate and polyethylene glycol, followed by chromatography on DEAE–cellulose. The purification factor was 100–200 × and the overall yield was about 115%. The enzyme was chemically attached to derivatives of cellulose and the kinetics of these insolubilized penicillin amidase preparations was investigated.     

SUMO fosters assembly and functionality of the MutSγ complex to facilitate meiotic crossing over

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