Downstream processing phenylalanine from fermentation

The culture can be used directly for the conversion of phenylpyruvic add to resting cells L-phenylalanine. Therefore, a batch process with resting cells can be carried out, with some glucose added for maintenance (fed-batch fermentation). Another approach is to harvest the cells from the fermentation broth and to use them in a separate bioreactor in higher concentrations than the ones obtained in the cell cultivation. An advantage of the last method can be that the concentration of compounds other than L-phenylalanine is lower, so that downstream processing may be cheaper. 

Applications of liquid emulsion membranes (LEMs) to biomedical and biochemical systems are reviewed and other potential applications identified. The LEM-mediated downstream processing of small, zwitterionic biochemicals (e.g. amino acids) is examined using chloride ion counter-transport to separate and concentrate the amino acid phenylalanine from stimulated fermentation broth. The effect of agitation rate and osmotic swelling of membranes on separation is shown to be significant. 

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