What Is Pyruvic Acid?

Pyruvate, also known as a-oxopropanoic acid, has a structure of C H3CO CO OH. It is an important intermediate for the sugar metabolism of all biological cells and the conversion of various substances in the body. Because the molecule contains activated ketones and carboxyl groups, A basic chemical raw material is widely used in various fields such as chemistry, pharmacy, food, agriculture and environmental protection, and can be prepared through various methods such as chemical synthesis and biotechnology.

Chinese name: pyruvate.

Chinese synonym: 2-oxopropionic acid; acetoformic acid; pyruvate; A-ketopropionic acid; acetic acid; pyruvate PYRUVIC ACID; acetyl formic acid; pyruvate.

English name: Pyruvic acid.

Pyruvic acid tartaric acid dehydration decarboxylation method

The process of this method is simple and easy: the mixture of tartaric acid and potassium hydrogen sulfate is distilled at 220 ° C., and the distillate is subjected to vacuum distillation to obtain pyruvate. The characteristic of this method is that after adding heat-conducting oil, the reaction is performed in a homogeneous system, which reduces the reaction temperature, reduces the degree of oxidation, and greatly improves the operability. It is suitable for continuing the reaction to produce pyruvate series products. The disadvantage is that the yield of pyruvate is relatively low, and 5 g of potassium hydrogen sulfate is consumed to obtain 1 g of pyruvate. The cost of raw materials alone amounts to 80,000 yuan per ton, which is too high for most manufacturers to accept. ^[3]

Pyruvate- lactic acid oxidation

Pyruvate is produced by oxidative dehydrogenation in one step from lactic acid. However, it is very difficult to directly prepare pyruvate from lactic acid, and it is necessary to select a suitable catalyst according to different processes. The catalysts that can be selected are iron phosphate, tellurium molybdate, silver, vanadium and the like. Compared with the oxidative decarboxylation method of tartaric acid, this method has the advantages of low energy consumption, small pollution, high yield, etc., and is suitable for industrial production. The disadvantage is that the cost is also high, about 60,000 yuan per ton. ^[3]

Pyruvate catalysis

Enzymes or microbial cells are used as catalysts to convert certain intermediate metabolites of glucose or tricarboxylic acid cycles to pyruvate under certain conditions, called enzyme catalysis. The main process is to carry out small-scale microbial culture, collect bacterial cells, directly transform or embed the carrier into an immobilized enzyme, and then convert to pyruvate. ^[4] Enzyme catalytic equipment has a small investment, low energy consumption and high conversion rate, but the substrate source is narrow and the cost is about 50,000 yuan per ton, so its further promotion is limited.

Pyruvate genetic engineering technology

Gene recombination technology is used to construct genetically engineered bacteria that highly express glycolate oxidase, catalase, etc., and are used to produce pyruvate. These enzymes catalyze the reaction of lactic acid with oxygen to generate pyruvate. Its technology is to first recombinate the glycolate oxidase gene and catalase gene with the DNA vector to form a recombinant, and transfer them into the host cell, respectively, to obtain genetically engineered yeasts with high expression of the two enzymes. The LL-sodium lactate solution was humidified with 5g of the transformant per 100ml, and a certain amount of penetrant was added. At 5 atmospheres, oxygen was introduced at 70psig oxygen pressure, and the mixture was stirred and converted at 5 ° C for 4 hours. The yield of pyruvate was 97.7% higher. The substrate conversion rate of this technology is high, but the technology is difficult. ^[3]

Pyruvate microbial fermentation

In the process of microbial metabolism, the process of using pyruvate to accumulate glucose is called microbial fermentation. The research on the production of pyruvate by microbial fermentation has a history of 50 years, but the selection and breeding of pyruvate-producing strains is very difficult. Although some microorganisms can accumulate pyruvate, the yield cannot meet the industrial requirements. A real breakthrough in the production of pyruvate by this method was in 1988. Researchers from Japan's Toray Industries Co., Ltd., Reiko Miyata and Mihara Taki, bred a series of Pseudomonas yeast strains with a pyruvate production of more than 50 g / L, enabling microorganisms Industrial production of pyruvate by fermentation is possible. In 1992, Japan began to produce pyruvate by microbial fermentation. The output is 400 tons per year and the cost is about 2-3 million yuan per ton. ^[3]

Compared with the chemical synthesis method and the enzyme conversion method, the microbial fermentation method is superior because of the wide source of raw materials, low energy consumption, less pollution, and low cost. However, the disadvantage of microbial fermentation is that the conversion rate is relatively low. This is because pyruvate is a key intermediate product of the glycolytic pathway. In cells, pyruvate as an important intermediate metabolite connects the EMP and TCA central metabolic pathways. It is also related to multiple branch metabolic pathways, which can be transformed into various fermentation products and cannot be accumulated in the body. Therefore, its further metabolism needs to be cut off or weakened in order to make it accumulate in the cells in large quantities. That is, to accelerate the conversion rate of glucose to pyruvate, reduce the flux to the TCA cycle, cut off or weaken its branch metabolic pathways, promote secretion, weaken the reuse of pyruvate, and finally achieve a large accumulation of pyruvate. In order to achieve this goal, it is necessary to study the influencing factors of pyruvate production by microbial fermentation.

The influencing factors of pyruvate production by microbial fermentation include: breeding of strains, nutritional conditions, vitamin levels, oxygen supply mode, glucose concentration and so on. The most critical is breeding and nutritional conditions of strains. ^[5]