Angelica Yeast Bacteria Fermentation Excellent Production of Amino Acids

May 10, 2013, "the second new organic nitrogen source application and development seminar" held in Guangxi Liucheng, 168 domestic and foreign association leaders, business representatives, experts, professional and technical personnel attended the meeting. At the meeting, Dr. Xu Qingyang of Tianjin University of Science and Technology, on behalf of well-known experts in the field of amino acid fermentation, gave a lecture entitled "Selection and Process Control of Nitrogen Sources for Production of Amino Acids by Fermentation of Engineering Bacteria".

According to Dr. Xu Qingyang, in the production of amino acid fermentation, the application of engineering engineering technology to build more and more engineering bacteria, so engineering bacteria fermentation medium selection and process control has become the focus of attention. Engineering bacteria with a foreign gene, its fermentation has its own unique characteristics. The stability of foreign genes is critical. The way to increase the stability of exogenous genes, including the selection of vectors and hosts in the upstream transformation of the cells, the application of selective pressure, the control of overexpression of genes and the control of culture conditions. Dr. Xu Qingyang emphasized the importance of increasing the stability of foreign genes by temperature, pH and DO. Usually low temperature is conducive to the genetic stability of foreign genes; too low dissolved oxygen concentration led to a large number of acetic acid production, cell growth was inhibited, plasmid stability decreased. In addition, Dr. Xu also pointed out that in the genetic engineering cell culture project, the expression efficiency and plasmid copy number. On the basis of plasmid stability, as much as possible to improve the number of intracellular plasmid copy.

For the selection of carbon sources in the amino acid producing strain medium, the low or too high initial sugar concentration is not conducive to cell growth and acid production. During the fermentation process, the low glucose concentration in the fermentation broth was maintained, the cell growth rate was smaller, the plasmid was stable, and the amount of acetic acid was less.

For the fermentation of engineering bacteria, the organic nitrogen source is a very important influencing factor. The contents of total nitrogen, amino nitrogen and amino acid in the organic nitrogen source are higher than the growth rate, the growth rate, the number of plasmid copies, the stability of the plasmid, The effect of expressing vigor is great. Engineering bacteria fermentation medium is generally selected with fast and slow use of mixed nitrogen source. The available nitrogen source is beneficial to the use of the cells and promote the growth of the cells. The slow nitrogen source prolongs the secretion period of the metabolites and increases the yield of the products. However, the one-time input is also easy to promote the growth of the cells and the premature depletion of nutrients. Early aging and autolysis.

According to Dr. Xu Qingyang, in many organic nitrogen sources, yeast leaching powder contains a large number of free amino acids, used in engineering bacteria amino acid fermentation, reducing the demand for bacterial synthesis and metabolism, reducing the rate of sugar than the final reduction of fermentation process acetic acid The release of acetic acid on cell growth and acid production inhibition. Yeast leaching powder as an engineered amino acid fermentation of organic nitrogen source for the growth of bacteria and amino acid synthesis of the most favorable.


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