The core technology of Dongguk University controls the pH during the enzyme response and provides the manufacturing method of the GABA (gamma-aminobutyric acid) not generating the salt after the response.
Background and unmet needs
The technical methods for GABA production include the synthetic process, the extraction method, and the bioconversion method. In case of the synthetic process, the used solvent is usually toxic. The extraction method has the disadvantages of a lot of waste generation and the high GABA manufacturing cost.
In case of the bioconversion method, pH is increased as the GABA is generated by the enzyme catalyst. Accordingly, the response slows down gradually and stops. Therefore, in order to continue the response, the acid must be put in to adjust pH.
Traditionally, pH of the response solution was adjusted by putting in the acid such as the hydrochloric acid, the sulfuric acid, the nitric acid, the acetic acid, and so on as the pH control agent as the response continues after setting the optimal pH with a buffering solution or a substrate . However, it had a problem with the generation of a lot of salt by adding the acid in proportion with the quantity of the GABA generated during the response.
In order to remove the generated salt, the purification processes such as the ion exchange resin process and recrystallization are needed. A lot of salt during the response causes the problems such as yield decline, waste generation, and so on so that the salt generation becomes the important factor increasing the GABA production cost.
Discovery and Achievements
The enzyme gamma-aminobutyric acid (GABA) production response was performed by using the solid acid within the distilled water without the buffering solution. Due to the 1,000 mM L-MSG substrate, pH within the response substrate was neutral before the solid acid was put in. However, putting in the solid acid made pH decreased so that it became lightly acidic to be suitable to enzyme activation. Thereafter, pH was increased by the enzyme response. However, the final conversion rate was 70% so that it was improved greatly compared to 16%. The gamma-aminobutyric acid (GABA) could be produced efficiently without salt generation.