Whole-cell catalysts Escherichia coli

An (5)-specific alcohol dehydrogenase gene from Rhodococcus erythropolis and GDH from Bacillus subtilis were ligated into one plasmid, which was expressed in Escherichia coli strain DSM14 459 to provide an (S)-selective whole-cell catalyst. 

A biocatalytic enantioselective addition of ammonia to a C=C bond of an afl-unsaturated compound, namely fumaric acid, makes the manufacture of L-aspar-tic acid, l-27, possible [30], This L-amino acid represents an important intermediate for the production of the artificial sweetener aspartame. The biocatalytic production process, which is applied on an industrial scale by, e.g., Kyowa Hakko Ko-gyo and Tanabe Seiyaku, is based on the use of an aspartate ammonia lyase [E.C.4.3.1.1] [31]. As a biocatalyst, an immobilized L-aspartate ammonia lyase from Escherichia coli [32, 33] as well as Brevibacterium flavum whole-cell catalysts [32 a, 34] have been applied successfully. 

Subsequently, bienzymatic whole cell catalysts were constracted by coexpressing the (S)-HnL and nitrilase activities simultaneously in the yeast Pichia pastoris and the bacterium Escherichia coli. The recombinant E. coU cells exhibited much higher HnL and nitrilase activities compared to the P. pastoris catalysts and were therefore studied in greater detail [63, 64]. The recombinant E. coli cells were... 

A. (2012) Application of a recombinant Escherichia coli whole-cell catalyst expressing hydroxynitrile lyase and nitrilase activities in ionic liquids for the production of (S)-mandelic acid and (S)-mandeloamide. Adv. Synth. Catal., 354, 113-122. 

Since 1978, several papers have examined the potential of using immobilised cells in fuel production. Microbial cells are used advantageously for industrial purposes, such as Escherichia coli for the continuous production of L-aspartic acid from ammonium fur-marate.5,6 Enzymes from microorganisms are classified as extracellular and intracellular. If whole microbial cells can be immobilised directly, procedures for extraction and purification can be omitted and the loss of intracellular enzyme activity can be kept to a minimum. Whole cells are used as a solid catalyst when they are immobilised onto a solid support. 

The biocatalytic reduction of carboxylic acids to their respective aldehydes or alcohols is a relatively new biocatalytic process with the potential to replace conventional chemical processes that use toxic metal catalysts and noxious reagents. An enzyme known as carboxylic acid reductase (Car) from Nocardia sp. NRRL 5646 was cloned into Escherichia coli BL21(DE3). This E. coli based biocatalyst grows faster, expresses Car, and produces fewer side products than Nocardia. Although the enzyme itself can be used in small-scale reactions, whole E. coli cells containing Car and the natural cofactors ATP and NADPH, are easily used to reduce a wide range of carboxylic acids, conceivably at any scale. The biocatalytic reduction of vanillic acid to the commercially valuable product vanillin is used to illustrate the ease and efficiency of the recombinant Car E. coli reduction system." A comprehensive overview is given in Reference 6, and experimental details below are taken primarily from Reference 7. 

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