Efficient conversion of dinitrile to mononitrile-monocarboxylic acid by Corynebacterium sp. C5 cells during tranexamic acid synthesis

Abstract

Use of peptone and yeast extract as the nitrogen source together with glucose as the carbon source was effective in the culture of Corynebacterium sp. C5 cells that convert trans -1,4-dicyanocyclohexane ( t -DCC) to trans -4-cyanocyclohexane-1-carboxylic acid ( t -MCC). The ratio of nitrile hydratase to amidase that converted t -DCC to t -MCC was 3 : 1, but the stability of the nitrile hydratase was one-tenth that of the amidase. Potassium phosphate buffer (pH 8.5) stabilized the two enzymes and produced maximum activity. High yields of t -MCC (99.4%) were produced from a high concentration of t -DCC (40%) in a resting cell system. t -DCC crystals disappeared, with the solution becoming clear as the reaction proceeded. The tranexamic acid synthesized from the t -MCC produced by the resting cells was of very high quality; 99.97% trans -isomer.