Fed-batch biotransformation

Table 12.4 Fed-batch biotransformation of (R,S)-linalool by C. cassiicola DSM 62475 using Procedures 1 and 2. Of 340 mgf (R,S)-linalool added, 96 % was consumed...

More recently, the fed-batch biotransformation of / -ionone by Aspergillus niger was described [126]. A commercially available strain, A. niger IFO 8541 was selected and was found to be an efficient biocatalyst for the biotransformation of / -ionone into 2- and 4-hydroxy-/ -ionone and 2-oxo-/ -ionone. 4-Hydroxy-/ -ionone was the main product with a mass yield close to 90%. It is interesting to note that the metabolism of / -ionone involves a lag phase, which is a function of the... 

Prediction of benzaldehyde pulse feeding profile to optimize the production of PAC in fed batch PAC biotransformation process at 6°C. A molar ratio of 1.2 1 pyruvate to benzaldehyde was used, with AR grade benzaldehyde and a 1.4 M solution of pyruvate used in the simulated feeding. 

Simulation profile of fed batch PAC biotransformation kinetics at 6°C with initial PDC activity of 4.0 U carboligase ml, 90 mM benzaldehyde and 108 mM sodium pyruvate. Feeding was performed hourly as illustrated in Fig. 3 and the initial reaction volume of 30 ml (which would be used experimentally) increased to 45 ml at the end of reaction. 

Fed- batch PAC biotransformation kinetics at 6°C with optimal feeding program. Initial and final reaction volumes after 81 h were 30 and 45 ml, respectively. The biotransformation was carried out in 2.5 M MOPS, 1 mM MgS04,1 mM TPP with initial pH of 6,5 and initial carboligase activity of 3.82 U mf. The pH adjustment was performed manually using 30% (v/v) H2SO4. 

An example of a process where the fed-batch mode has a decisive advantage over a continuous operation is the biotransformation of y-butyrobetaine into L-carnitine. This fine chemical has pharmacological, nutritional, and animal-feed applications, making product purification an essential part of the production process. Consequently, process optimization of biotransformation and downstream... 

The product is applied for the treatment of Parkinsonism that is caused by a lack of l-dopamine and its receptors in the brain. L-Dopamine is synthesized in organisms by decarboxylation of L-3,4-dihydroxyphenylalanine (L-dopa). Since L-dopamine cannot pass the blood-brain barrier L-dopa is applied in combination with dopadecarbox-ylase-inhibitors to avoid formation of L-dopamine outside the brain. Ajinomoto produces L-dopa by this lyase-biotransformation with suspended whole cells in a fed batch reactor on a scale of 250 t a-1. Much earlier, Monsanto has successfully scaled up the chemical synthesis of L-dopa (Fig. 19-38). 

At the same time, engineering rules that apply to whole-cell redox reactions have to be taken into account. In general, aeration and/or carbon dioxide production is involved, and plug flow reactors are not appropriate. Moreover, oxygen transfer to immobilized cells is not very efficient. Consequently, continuous reactors are not very suitable for redox biotransformations with whole cells [12]. These biotransformations can best be carried out in (fed) batch reactors with free cells. Since the production of the cells will also involve a (fed) batch process, these processes may easily be combined. Then, the cells are produced in a fed-batch fer-... 

A fed batch process using suspended Rhodotorula rubra cells in an aqueous medium at pH 10.6 was developed [263]. Since PAL from R. rubra is oxygen-sensitive, the biotransformation is performed under anaerobic, static condition in fed batch mode with periodic addition of concentrated ammonium dnnamate solution and pH maintenance by CO addition [263]. The fermentative process was improved by starting the process direcdy from glucose as a substrate and L-phenylalanine is now manufactured by fermentation on a scale of 8-10,000 tons per year [264]. 

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